SEACOR Marine (SMHI) S-3 Shelf registration

As filed with the Securities and Exchange Commission on February 7, 2025

Registration Statement No. 333-   

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

WASHINGTON, D.C. 20549

FORM S-3

REGISTRATION STATEMENT

UNDER

THE SECURITIES ACT OF 1933

SEACOR MARINE HOLDINGS INC.

(Exact name of Registrant as specified in its charter)

Delaware	47-2564547
(State or other jurisdiction of incorporation or organization)	(I.R.S. Employer Identification Number)

12121 Wickchester Lane, Suite 500

Houston, TX 77079

(346) 980-1700

(Address, Including Zip Code, and Telephone Number, Including Area Code, of Registrant’s Principal Executive Offices)

John Gellert

President and Chief Executive Officer

SEACOR Marine Holdings Inc.

12121 Wickchester Lane, Suite 500

Houston, TX 77079

(346) 980-1700

(Name, Address, Including Zip Code, and Telephone Number, Including Area Code, of Agent for Service)

Copies to:

Brett Nadritch	Andrew H. Everett II
Milbank LLP 55 Hudson Yards New York, NY 10001 (212) 530-5301	Senior Vice President, General Counsel and Secretary SEACOR Marine Holdings Inc. 12121 Wickchester Lane, Suite 500 Houston, TX 77079 (346) 980-1700

Approximate date of commencement of proposed sale to the public: From time to time after the effective date of this registration statement.

If the only securities being registered on this Form are being offered pursuant to dividend or interest reinvestment plans, please check the following box: ☐

If any of the securities being registered on this Form are to be offered on a delayed or continuous basis pursuant to Rule 415 under the Securities Act of 1933, as amended, or the Securities Act other than securities offered only in connection with dividend or interest reinvestment plans, check the following box: ☒

If this Form is filed to register additional securities for an offering pursuant to Rule 462(b) under the Securities Act, please check the following box and list the Securities Act registration statement number of the earlier effective registration statement for the same offering. ☐

If this Form is a post-effective amendment filed pursuant to Rule 462(c) under the Securities Act, check the following box and list the Securities Act registration statement number of the earlier effective registration statement for the same offering. ☐

If this Form is a registration statement pursuant to General Instruction I.D. or a post-effective amendment thereto that shall become effective upon filing with the Commission pursuant to Rule 462(e) under the Securities Act, check the following box. ☐

If this Form is a post-effective amendment to a registration statement filed pursuant to General Instruction I.D. filed to register additional securities or additional classes of securities pursuant to Rule 413(b) under the Securities Act, check the following box. ☐

Indicate by check mark whether the registrant is a large accelerated filer, an accelerated filer, a non-accelerated filer, a smaller reporting company, or an emerging growth company. See the definitions of “large accelerated filer,” “accelerated filer,” “smaller reporting company,” and “emerging growth company” in Rule 12b-2 of the Securities Exchange Act of 1934, as amended, or the Exchange Act.

Large accelerated filer	☐	Accelerated filer	☒
Non-accelerated filer	☐	Smaller reporting company	☐
		Emerging growth company	☐

If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 7(a)(2)(B) of the Securities Act. ☐

The Registrant hereby amends this registration statement on such date or dates as may be necessary to delay its effective date until the Registrant shall file a further amendment that specifically states that this registration statement shall thereafter become effective in accordance with Section 8(a) of the Securities Act or until the registration statement shall become effective on such date as the Securities and Exchange Commission, acting pursuant to said Section 8(a), may determine.

EXPLANATORY NOTE

This registration statement contains two prospectuses:

• a base prospectus, which covers the offering, issuance and sale by us of up to $200,000,000 in the aggregate of our common stock, preferred stock, warrants and/or units consisting of some or all of these securities; and

• a sales agreement prospectus covering the offering, issuance and sale by us of up to a maximum aggregate offering price of $25,000,000 of shares of our common stock pursuant to At Market Issuance Sales Agreement (“sales agreement”) dated February 7, 2025, with B. Riley Securities, Inc.

The base prospectus immediately follows this explanatory note. The specific terms of any securities to be offered pursuant to the base prospectus will be specified in a prospectus supplement to the base prospectus. The sales agreement prospectus immediately follows the base prospectus. Upon termination of the sales agreement with B. Riley Securities, Inc., any portion of the $25,000,000 of securities included in the sales agreement prospectus that remains unsold pursuant to the sales agreement will be available for sale in other offerings pursuant to the base prospectus and a corresponding prospectus supplement, and if no shares are sold under the sales agreement, the full $25,000,000 of securities not sold may be sold in other offerings pursuant to the base prospectus and a corresponding prospectus supplement.

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The information in this prospectus is not complete and may be changed. We may not sell these securities or accept an offer to buy these securities until the registration statement filed with the Securities and Exchange Commission is effective. This prospectus is not an offer to sell these securities, and it is not soliciting offers to buy these securities in any jurisdiction where such offer or sale is not permitted.

SUBJECT TO COMPLETION, DATED FEBRUARY 7, 2025

PROSPECTUS

$200,000,000

Common Stock

Preferred Stock

Warrants

Units

We may, from time to time, offer and sell up to $200,000,000 of any combination of our common stock, preferred stock, or warrants described in this prospectus, either individually or in combination with other securities, at prices and on terms described in one or more supplements to this prospectus. We may also offer common stock upon conversion of preferred stock, or common stock or preferred stock upon the exercise of warrants. We may also authorize one or more free writing prospectuses to be provided to you in connection with these offerings.

Each time we offer securities, to the extent applicable, we will provide the specific terms of the securities offered in one or more supplements to this prospectus. We may also authorize one or more free writing prospectuses to be provided to you in connection with these offerings. Any such prospectus supplement and any related free writing prospectus may also add, update or change information contained in this prospectus. You should carefully read this prospectus, the applicable prospectus supplement and any related free writing prospectus, as well as any documents incorporated by reference, before buying any of the securities being offered.

The securities offered by this prospectus may be sold directly to investors, through agents designated from time to time or to or through underwriters or dealers. We will set forth the names of any underwriters or agents and any applicable fees, commissions, discounts and over-allotments in an accompanying prospectus supplement. For additional information on the methods of sale, you should refer to the section entitled “Plan of Distribution” in this prospectus and in the applicable prospectus supplement. The price to the public of such securities and the net proceeds we expect to receive from such sale will also be set forth in a prospectus supplement.

Our common stock is traded on the New York Stock Exchange (“NYSE”) under the symbol “SMHI.” On February 3, 2025, the last reported sale price of a share of our common stock on the NYSE was $6.79. The applicable prospectus supplement will contain information, where applicable, as to any other listing, if any, on the NYSE or any securities market or other exchange of the securities covered by the applicable prospectus supplement.

Investing in our securities involves a high degree of risk. You should review carefully the risks and uncertainties referenced under the heading “risk factors“ on page 6 of this prospectus as well as those contained in the applicable prospectus supplement (if any) and any related free writing prospectus, and in the documents that are incorporated by reference into this prospectus.

Neither the Securities and Exchange Commission nor any state securities commission has approved or disapproved of these securities or determined if this prospectus is truthful or complete. Any representation to the contrary is a criminal offense.

The date of this prospectus is February , 2025

TABLE OF CONTENTS

	Page
ABOUT THIS PROSPECTUS		1
SUMMARY		2
RISK FACTORS		6
FORWARD-LOOKING STATEMENTS		7
USE OF PROCEEDS		10
DETERMINATION OF OFFERING PRICE		11
PLAN OF DISTRIBUTION		12
DESCRIPTION OF CAPITAL STOCK		14
DESCRIPTION OF WARRANTS		19
DESCRIPTION OF UNITS		21
LEGAL MATTERS		22
EXPERTS		23
WHERE YOU CAN FIND ADDITIONAL INFORMATION		24
INCORPORATION OF CERTAIN INFORMATION BY REFERENCE		25

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ABOUT THIS PROSPECTUS

This prospectus is part of a registration statement on Form S-3 that we filed with the Securities and Exchange Commission, or the SEC, utilizing a “shelf” registration process. Under this shelf registration process, we may offer shares of our common stock, preferred stock, and/or warrants to purchase our common stock or preferred stock, either individually or in units, in one or more offerings, up to a total dollar amount of $200,000,000. This prospectus provides you with a general description of the securities we may offer. Each time we offer a type or series of securities under this prospectus, to the extent required, we will provide a prospectus supplement that will contain more specific information about the specific terms of the offering. We may also authorize one or more free writing prospectuses to be provided to you that may contain material information relating to these offerings. Each such prospectus supplement (and any related free writing prospectus that we may authorize to be provided to you) may also add, update or change information contained in this prospectus or in documents incorporated by reference into this prospectus. We urge you to carefully read this prospectus, any applicable prospectus supplement and any related free writing prospectus, together with the information incorporated herein by reference as described under the headings “Where You Can Find Additional Information” and “Incorporation of Certain Information by Reference” before buying any of the securities being offered. We will deliver a prospectus supplement with this prospectus, to the extent appropriate, to update the information contained in this prospectus.

You should rely only on the information contained or incorporated by reference in this prospectus, any applicable prospectus supplement and any related free writing prospectus. We have not authorized anyone to provide you with different information in addition to or different from that contained in this prospectus, any applicable prospectus supplement and any related free writing prospectus. No dealer, salesperson or other person is authorized to give any information or to represent anything not contained in this prospectus, any applicable prospectus supplement or any related free writing prospectus that we may authorize to be provided to you. You must not rely on any unauthorized information or representation. This prospectus is an offer to sell only the securities offered hereby, but only under circumstances and in jurisdictions where it is lawful to do so. You should assume that the information in this prospectus, any applicable prospectus supplement or any related free writing prospectus is accurate only as of the date on the front of the document and that any information incorporated by reference is accurate only as of the date of the document incorporated by reference, regardless of the time of delivery of this prospectus, any applicable prospectus supplement or any related free writing prospectus, or any sale of a security.

This prospectus contains summaries of certain provisions contained in some of the documents described herein, but reference is made to the actual documents for complete information. All of the summaries are qualified in their entirety by the actual documents. Copies of some of the documents referred to herein have been filed, will be filed or will be incorporated by reference as exhibits to the registration statement of which this prospectus is a part, and you may obtain copies of those documents as described below under the heading “Where You Can Find Additional Information.”

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SUMMARY

This summary highlights selected information from this prospectus or incorporated by reference in this prospectus, and does not contain all of the information that you need to consider in making your investment decision. You should carefully read the entire prospectus, the applicable prospectus supplement and any related free writing prospectus, including the risks of investing in our securities contained in the applicable prospectus supplement and any related free writing prospectus, and in the other documents that are incorporated by reference into this prospectus. You should also carefully read the information incorporated by reference into this prospectus, including our financial statements, and the exhibits to the registration statement of which this prospectus is a part.

Unless otherwise indicated or unless the context otherwise requires, references in this prospectus to the “Company,” “SEACOR Marine,” “SMHI,” “we,” “us,” or “our” are to SEACOR Marine Holdings Inc. and its subsidiaries.

Overview

The Company provides global marine and support transportation services to offshore energy facilities worldwide. As of September 30, 2024, the Company operated a diverse fleet of 55 support vessels, of which 54 were owned or leased-in and one was managed on behalf of an unaffiliated third party. The primary users of the Company’s services are major integrated national and international oil companies, independent oil and natural gas exploration and production companies, oil field service and construction companies, as well as offshore wind farm operators and offshore wind farm installation and maintenance companies.

The Company operates and manages a diverse fleet of offshore support vessels that (i) deliver cargo and personnel to offshore installations, including offshore wind farms, (ii) assist offshore operations for production and storage facilities, (iii) provide construction, well work-over, offshore wind farm installation and decommissioning support, (iv) carry and launch equipment used underwater in drilling and well installation, maintenance, inspection and repair and (v) handle anchors and mooring equipment for offshore rigs and platforms. Additionally, the Company’s vessels provide emergency response services and accommodations for technicians and specialists.

The Company operates its fleet in four principal geographic regions: the United States (“U.S.”), primarily in the Gulf of Mexico; Africa and Europe; the Middle East and Asia; and Latin America, primarily in Mexico and Guyana. The Company’s vessels are highly mobile and regularly and routinely move between countries within a geographic region. In addition, the Company’s vessels are redeployed among geographic regions, subject to flag restrictions, as changes in market conditions dictate. The number and type of vessels operated, their rates per day worked and their utilization levels are the key determinants of the Company’s operating results and cash flows.

Corporate Information

Our principal executive offices are located at 12121 Wickchester Lane, Suite 500, Houston, TX 77079, and our telephone number is (346) 980-1700. Additional information about us is available on our website at www.seacormarine.com. The information contained on or that may be obtained from our website is not, and shall not be deemed to be, a part of this prospectus. You can review filings we make with the SEC at its website (www.sec.gov), including our annual reports on Form 10-K, quarterly reports on Form 10-Q, current reports on Form 8-K and amendments to those reports electronically filed or furnished pursuant to Section 15(d) of the Exchange Act.

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The Securities That May Be Offered

We may offer shares of our common stock, various series of preferred stock and/or warrants to purchase our common stock or preferred stock, either individually or in units, with a total aggregate value of up to $200,000,000 from time to time under this prospectus at prices and on terms to be determined at the time of any offering. This prospectus provides you with a general description of the securities we may offer. Each time we offer a type or series of securities under this prospectus, to the extent applicable, we will provide a prospectus supplement that will describe the specific amounts, prices and other important terms of the securities, including, to the extent applicable:

• designation or classification;

• rates and times of payment of interest or dividends, if any;

• redemption, conversion, exchange or sinking fund terms, if any;

• conversion or exchange prices or rates, if any, and, if applicable, any provisions for changes to or adjustments in the conversion or exchange prices or rates and in the securities or other property receivable upon conversion or exchange;

• restrictive covenants, if any; and

• voting or other rights, if any.

The prospectus supplement and any related free writing prospectus that we may authorize to be provided to you may also add, update or change information contained in this prospectus or in the documents we have incorporated by reference. However, no prospectus supplement or free writing prospectus will offer a security that is not registered and described in this prospectus at the time of the effectiveness of the registration statement of which this prospectus is a part.

We may sell the securities directly to investors or to or through agents, underwriters or dealers. We and our agents or underwriters reserve the right to accept or reject all or part of any proposed purchase of securities. If we do offer securities to or through agents or underwriters, to the extent required, we will include in the applicable prospectus supplement:

• the names of those agents or underwriters;

• applicable fees, discounts and commissions to be paid to them;

• details regarding over-allotment options, if any; and

• the net proceeds to us.

To facilitate compliance with the Jones Act, the Company’s third amended and restated certificate of incorporation (the “Certificate of Incorporation”) and third amended and restated bylaws (the “Bylaws”): (i) limit (a) the aggregate percentage ownership by non-U.S. citizens of any class of the Company’s capital stock (including common stock) to 22.5% of the outstanding shares of each such class to ensure that ownership by non-U.S. citizens will not exceed the maximum percentage permitted by applicable maritime law (presently 25%) but authorize the Company’s board of directors, under certain circumstances, to increase the foregoing percentage to not more than 24% and (b) ownership of shares of any class or series of its capital stock by a single non-U.S. citizen (and any other non-U.S. citizen whose ownership position would be aggregated with such non-U.S. citizen for purposes of the Jones Act) to not more than 4.9% of the outstanding shares of each such class or series (each such limitation, the “Permitted Percentage”); (ii) allow for the institution of a dual stock certification system to help determine such ownership; (iii) provide that any issuance or transfer of shares in excess of the Permitted Percentage shall be ineffective as against the Company and that neither the Company nor

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its transfer agent shall register such purported issuance or transfer of shares or be required to recognize the purported transferee or owner as a stockholder of the Company for any purpose whatsoever except to exercise the Company’s remedies under the Certificate of Incorporation; (iv) provide that any excess shares above the Permitted Percentage shall not have any voting or dividend rights; (v) permit the Company to redeem or transfer to a charitable trust any such excess shares; and (vi) permit the board of directors to make such reasonable determinations as may be necessary to ascertain such ownership and implement such limitations. In addition, the Company’s Bylaws provide (w) that the number of non-U.S. citizen directors shall not exceed a minority of the number necessary to constitute a quorum for the transaction of business, (x) for an increase in the number of directors necessary to constitute a quorum when the number of non-U.S. citizen directors is equal to or greater than 50% of the number of directors present at a meeting, (y) that the President and the Chief Executive Officer of the Company must be a U.S. citizen and (z) that any non-U.S. citizen officer is restricted from acting in the absence or disability of the chairman of the board of directors, the Chief Executive Officer or the President.

Common Stock. We may issue shares of our common stock from time to time. Holders of shares of our common stock are entitled to one vote for each share on all matters submitted to a vote of stockholders and do not have cumulative voting rights. The common stock votes together as a single class. Directors are elected by a plurality of the votes of the shares of common stock present in person or by proxy at a meeting of stockholders and voting for nominees in the election of directors. Except as otherwise provided in our Certificate of Incorporation or Bylaws or required by law, all other matters to be voted on by our stockholders must be approved by a majority of the shares present in person or by proxy at a meeting of stockholders and entitled to vote on the subject matter. Holders of common stock are entitled to receive proportionately any dividends as may be declared by our board of directors, subject to any preferential dividend rights of outstanding preferred stock. Upon our liquidation, dissolution or winding up, the holders of common stock are entitled to receive proportionately our net assets available after the payment of all debts and other liabilities and subject to the prior rights of any outstanding preferred stock. Holders of common stock have no preemptive, subscription, redemption or other conversion rights and do not have any sinking fund provisions. The rights, preferences and privileges of holders of common stock are subject to, and may be adversely affected by, the rights of the holders of shares of any series of preferred stock which we may designate and issue in the future. Shares of our common stock are not convertible into any other shares of our capital stock.

Preferred Stock. Our board of directors is authorized to provide for the issuance of preferred stock in one or more series and to fix the preferences, powers and relative, participating, optional or other special rights, and qualifications, limitations or restrictions thereof, including the dividend rate, conversion rights, voting rights, redemption rights and liquidation preference and to fix the number of shares to be included in any such series without any further vote or action by our stockholders. Any preferred stock so issued may rank senior to our common stock with respect to the payment of dividends or amounts upon liquidation, dissolution or winding up, or both. In addition, any such shares of preferred stock may have class or series voting rights. The issuance of preferred stock may have the effect of delaying, deferring or preventing a change in control of our company without further action by the stockholders and may adversely affect the voting and other rights of the holders of our common stock.

If we sell any series of preferred stock under this prospectus, we will fix the preferences, powers and relative, participating, optional or other special rights, and qualifications, limitations or restrictions thereof, including the dividend rate, conversion rights, voting rights, redemption rights and liquidation preference and to fix the number of shares to be included in any such series in the certificate of designation relating to that series. We will file as an exhibit to the registration statement of which this prospectus is a part, or will incorporate by reference from reports that we file with the SEC, the form of any certificate of designation that describes the terms of the series of preferred stock that we are offering before the issuance of the related series of preferred stock. We urge you to read the applicable prospectus supplement (and any free writing prospectus that we may

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authorize to be provided to you) related to the series of preferred stock being offered, as well as the complete certificate of designation that contains the terms of the applicable series of preferred stock.

Warrants. We may issue warrants for the purchase of common stock or preferred stock in one or more series. We may issue warrants independently or together with common stock or preferred stock. In this prospectus, we have summarized certain general features of the warrants that we may issue in the future. We urge you, however, to read the applicable prospectus supplement (and any free writing prospectus that we may authorize to be provided to you) related to the particular series of warrants being offered, as well as the complete warrant agreements and/or warrant certificates that contain the terms of the warrants. We will file as exhibits to the registration statement of which this prospectus is a part, or will incorporate by reference from reports that we file with the SEC, the forms of warrant agreement and/or warrant certificates that describe the terms of the series of warrants we are offering before the issuance of the related series of warrants.

We will evidence each series of warrants by warrant certificates that we will issue. Warrants may be issued under an applicable warrant agreement that we enter into with a warrant agent. We will indicate the name and address of the warrant agent, if applicable, in the prospectus supplement relating to the particular series of warrants being offered.

Units. We may issue, in one or more series, units consisting of common stock, preferred stock and/or warrants for the purchase of common stock or preferred stock in any combination. Each unit will be issued so that the holder of the unit is also the holder of each security included in the unit. In this prospectus, we have summarized certain general features of the units. We urge you, however, to read the applicable prospectus supplement (and any free writing prospectus that we may authorize to be provided to you) related to the series of units being offered, as well as the complete unit agreement, if any, which contains the terms of the units. We will file as exhibits to the registration statement of which this prospectus is a part, or will incorporate by reference from reports that we file with the SEC, any form of unit agreement and any supplemental agreements that describe the terms of the series of units we are offering before the issuance of the related series of units.

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RISK FACTORS

An investment in our securities involves a certain degree of risk. You should carefully consider the factors contained in our Annual Report on Form 10-K for the fiscal year ended December 31, 2023 under the heading “Risk Factors” and updated, if applicable, in our Quarterly Reports on Form 10-Q before investing in our securities. You should also consider similar information contained in any Annual Report on Form 10-K, Quarterly Report on Form 10-Q or other document filed by us with the SEC after the date of this prospectus before deciding to invest in our securities. If any of these risks were to occur, our business, financial condition or results of operations could be adversely affected. In that case, the trading price of our common stock or other securities could decline and you could lose all or part of your investment. When we offer and sell any securities pursuant to a prospectus supplement, we may include additional risk factors relevant to such securities in the prospectus supplement.

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FORWARD-LOOKING STATEMENTS

This prospectus, the documents incorporated by reference herein contain forward-looking statements within the meaning of Section 27A of the Securities Act of 1933, as amended, or the Securities Act, and Section 21E of the Securities Exchange Act of 1934, as amended (the “Exchange Act”). Such forward-looking statements concern management’s expectations, strategic objectives, business prospects, anticipated economic performance and financial condition and other similar matters and involve significant known and unknown risks, uncertainties and other important factors that could cause the actual results, performance or achievements of results to differ materially from any future results, performance or achievements discussed or implied by such forward-looking statements. All of these forward-looking statements constitute the Company’s cautionary statements under the Private Securities Litigation Reform Act of 1995. The words “anticipate,” “estimate,” “expect,” “project,” “intend,” “believe,” “plan,” “target,” “forecast” and similar expressions are intended to identify forward-looking statements. Forward-looking statements speak only as of the date of the document in which they are made. The Company disclaims any obligation or undertaking to provide any updates or revisions to any forward-looking statement to reflect any change in the Company’s expectations or any change in events, conditions or circumstances on which the forward-looking statement is based. Risks related to forward-looking statements include, but are not necessarily limited to, those relating to:

• fluctuating prices and decreased demand for oil and natural gas;

• decreased demand for offshore oil and natural gas exploration, development and production;

• public health emergencies and their impact and disruption to business operations and workforce;

• restrictions and limitations imposed by credit facilities on operating and financial flexibility;

• indebtedness;

• downward pricing pressures on the price of crude oil and natural gas resulting from unconventional crude oil and natural gas sources and improved economics of producing natural gas and oil from such sources;

• losses or impairment charges related to sold or idle vessels;

• increase in competition in the offshore marine service industry;

• oversupply of vessels or equipment serving offshore oil and natural gas operations may adversely impact charter rates for vessels and equipment;

• loss of significant customers;

• consolidation of customer base may adversely affect demand for services and reduction in revenue;

• inability to maintain or replace offshore support vessels as they age;

• failure to successfully complete construction or conversion of vessels, repairs, maintenance or routine dry dockings on schedule and on budget;

• inability to attract and retain qualified personnel and crew vessels appropriately;

• inability to improve operations and financial systems, and recruitment of additional staff;

• seasonal factors and their impact on business operations and workforce;

• incurring high levels of fixed costs regardless of business activity levels;

• incurring higher than expected costs to return previously cold-stacked vessels to class as the markets recovers or marketing strategies change;

• inflation and increased interest rates may increase operating costs and capital costs;

• inability to renew or replace expiring contracts for vessels;

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• early termination of vessel contracts may adversely affect operations;

• inability to protect against service interruptions, data corruption, cyber-based attacks or network security breaches;

• failure to comply with data protection and privacy laws could lead to financial penalties and reputational harm;

• increased domestic and international laws and regulations, including additional laws and regulations in the event of high-profile incidents;

• changes in federal government regulation of offshore resources for the production of oil and natural gas;

• changes in laws and regulations, including environmental laws and regulations that can adversely affect the cost, manner or feasibility of doing business;

• global climate change and changes to environmental regulations and environmental expectations;

• instability of political, military and economic conditions in foreign countries;

• business operation disruptions and exposure to liability caused by hazards inherent for the operation of vessels;

• ability to retain customers due to a failure to maintain an acceptable safety record;

• inadequacy of insurance coverage;

• inadequate indemnification by customers for damage to their property or the property of their other contractors;

• adverse effects and additional risks to business resulting from significant corporate transactions;

• prohibition of operation of offshore support vessels in the U.S. resulting from failure to restrict the amount of ownership of the Company’s common stock by non-U.S. citizens;

• repeal, amendment, suspension or non-enforcement of the Jones Act;

• inability to sell off a portion of the business or forfeiture of vessels resulting from restrictions placed on non-U.S. citizen ownership;

• restrictions placed by the Company’s incorporation and formation documents limiting ownership of common stock by individuals and entities that are not U.S. citizens may affect liquidity of common stock and may result in non-U.S. citizens being required to sell their shares at a loss or relinquish their voting, dividend and distribution rights;

• inability to access funds, redeem any excess shares and suspension of operations in the U.S. coastwise trade due to non-U.S. citizens owning more than 22.5% the Company’s common stock, as limited by our bylaws (which are stricter than the regulatory limit of 25%);

• requisition or use by governmental agencies of the Company’s vessels;

• inability to improve cash flow and liquidity through vessel sales resulting from inability to locate buyers with access to financing or to complete any sales on acceptable terms or within a reasonable time frame;

• inability to collect amounts owed by customers;

• lack of sole decision-making authority and disputes between joint ventures and investments in joint ventures;

• exposure to potential future losses due to participation in industry-wide, multi-employer, defined benefit pension plans;

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• federal law and state law job-related claims;

• fluctuations in common stock price;

• ownership dilution;

• common stock price and trading volume decline due to securities or industry analyst reports and recommendations;

• costs associated with the development and maintenance of proper and effective internal controls over financial reporting;

• failure to achieve and maintain effective internal controls over financial reporting;

• depression of common stock price due to provisions in the Company’s incorporation and formation documents that may discourage, delay or prevent a change of control of the Company or changes in the Company’s management;

• limitations to common stockholders’ ability to obtain favorable judicial forum for disputes due to forum selection clause restrictions placed by the Company’s incorporation and formation documents; and

• intention not to pay dividends on our common stock for the foreseeable future.

You should not place undue reliance on our forward-looking statements because the matters they describe are subject to known and unknown risks, uncertainties and other unpredictable factors, many of which are beyond our control. Our forward-looking statements are based on the information currently available to us and speak only as of the date on the cover of this prospectus. New risks and uncertainties arise from time to time, and it is impossible for us to predict these matters or how they may affect us. We have included important factors in the cautionary forward-looking statements included in this prospectus, particularly in the section of this prospectus entitled “Risk Factors,” which we believe, over time, could cause our actual results, performance or achievements to differ from the anticipated results, performance or achievements that are expressed or implied by our forward-looking statements. We have no duty to, and do not intend to, update or revise the forward-looking statements in this prospectus after the date of this prospectus except to the extent required by the federal securities laws. You should consider all risks and uncertainties disclosed in our filings with the Securities and Exchange Commission, or the SEC, described in the sections of this prospectus entitled “Where You Can Find More Information” and “Incorporation of Certain Information by Reference,” all of which are accessible on the SEC’s website at www.sec.gov.

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USE OF PROCEEDS

We will retain broad discretion over the use of the net proceeds from the sale of the securities offered by us hereby. Except as described in any prospectus supplement or any related free writing prospectus that we may authorize to be provided to you, we currently intend to use the net proceeds from the sale of the securities offered by us hereby for general corporate purposes, which may include capital expenditures, working capital and general and administrative expenses. We will set forth in the applicable prospectus supplement or free writing prospectus our intended use for the net proceeds received from the sale of any securities sold pursuant to the prospectus supplement or free writing prospectus. Pending these uses, we intend to invest the net proceeds in U.S. government or agency obligations, commercial paper, money market accounts, short-term marketable securities, bank deposits or certificates of deposit, repurchase agreements collateralized by U.S. government or agency obligations or other short-term investments.

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DETERMINATION OF OFFERING PRICE

We will offer the securities in amounts, at prices and on terms to be determined by market conditions at the time of the offerings.

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PLAN OF DISTRIBUTION

SEACOR Marine’s Plan of Distribution

We may sell the securities from time to time pursuant to underwritten public offerings, negotiated transactions, block trades or a combination of these methods. We may sell the securities to or through underwriters or dealers, through agents or directly to one or more purchasers. The securities may be distributed from time to time in one or more transactions:

• at a fixed price or prices, which may be changed;

• at market prices prevailing at the time of sale;

• at prices related to such prevailing market prices; or

• at negotiated prices.

Each time we offer and sell securities hereto, to the extent applicable, we will provide a prospectus supplement that will set forth the terms of the offering of the securities, including:

• the name or names of the underwriters, if any;

• the purchase price of the securities and the proceeds we will receive from the sale;

• any over-allotment options under which underwriters may purchase additional securities;

• any agency fees or underwriting discounts and other items constituting agents’ or underwriters’ compensation;

• any public offering price;

• any discounts or concessions allowed or re-allowed or paid to dealers; and

• any securities exchange or market on which the securities may be listed.

If underwriters are used in the sale, they will acquire the securities for their own account and may resell the securities from time to time in one or more transactions at a fixed public offering price or at varying prices determined at the time of sale. The obligations of the underwriters to purchase the securities will be subject to the conditions set forth in the applicable underwriting agreement. We may offer the securities to the public through underwriting syndicates represented by managing underwriters or by underwriters without a syndicate. Subject to certain conditions, the underwriters will be obligated to purchase all of the securities offered by the prospectus supplement, other than securities covered by any over-allotment option. Any public offering price and any discounts or concessions allowed or re-allowed or paid to dealers may change from time to time. We may use underwriters with whom we have a material relationship. The prospectus supplement, naming the underwriter, will describe the nature of any such relationship.

We may sell securities directly or through agents we or they designate from time to time. The prospectus supplement will name any agent involved in the offering and sale of securities and any commissions we will pay to them. Unless the prospectus supplement states otherwise, any agent will be acting on a best-efforts basis for the period of its appointment.

We may authorize agents or underwriters to solicit offers by certain purchasers to purchase securities from us at the public offering price set forth in the prospectus supplement pursuant to delayed delivery contracts providing for payment and delivery on a specified date in the future. The prospectus supplement will set forth the conditions to these contracts and any commissions we must pay for solicitation of these contracts.

We may provide agents and underwriters with indemnification against civil liabilities, including liabilities under the Securities Act, or contribution with respect to payments that the agents or underwriters may make with respect to these liabilities. Agents and underwriters may engage in transactions with, or perform services for, us in the ordinary course of business.

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Any securities we may offer, other than our common stock, will be new issues of securities with no established trading market. Any underwriters may make a market in these securities, but will not be obligated to do so and may discontinue any market making at any time without notice. We cannot guarantee the liquidity of the trading markets for any securities.

Any underwriter may engage in over-allotment, stabilizing transactions, short-covering transactions and penalty bids in accordance with Regulation M under the Exchange Act. Over-allotment involves sales in excess of the offering size, which create a short position. Stabilizing transactions permit bids to purchase the underlying security so long as the stabilizing bids do not exceed a specified maximum price. Syndicate-covering or other short-covering transactions involve purchases of the securities, either through exercise of the over-allotment option or in the open market after the distribution is completed, to cover short positions. Penalty bids permit the underwriters to reclaim a selling concession from a dealer when the securities originally sold by the dealer are purchased in a stabilizing or covering transaction to cover short positions. Those activities may cause the price of the securities to be higher than it would otherwise be. If commenced, the underwriters may discontinue any of the activities at any time.

Any underwriters that are qualified market makers on the NYSE may engage in passive market making transactions in the common stock on the NYSE in accordance with Regulation M under the Exchange Act, during the business day prior to the pricing of the offering, before the commencement of offers or sales of the common stock. Passive market makers must comply with applicable volume and price limitations and must be identified as passive market makers. In general, a passive market maker must display its bid at a price not in excess of the highest independent bid for such security; if all independent bids are lowered below the passive market maker’s bid, however, the passive market maker’s bid must then be lowered when certain purchase limits are exceeded. Passive market making may stabilize the market price of the securities at a level above that which might otherwise prevail in the open market and, if commenced, may be discontinued at any time.

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DESCRIPTION OF CAPITAL STOCK

General

Our authorized capital stock consists of 60,000,000 shares of common stock, par value $0.01 per share, and 10,000,000 shares of undesignated preferred stock, $0.01 par value per share, of which no preferred shares are issued or outstanding.

The following summary description of our capital stock is based on the provisions of our Certificate of Incorporation and Bylaws and the applicable provisions of the Delaware General Corporation Law (“DGCL”). This information is qualified entirely by reference to the applicable provisions of our Certificate of Incorporation, Bylaws and the DGCL. For information on how to obtain copies of our Certificate of Incorporation and Bylaws, please see “Where You Can Find Additional Information” and “Incorporation of Certain Information by Reference.”

Common Stock

As of January 31, 2025, there were 27,669,361 shares of our common stock outstanding. The holders of our common stock are entitled to the following rights.

Voting Rights

Holders of our common stock are entitled to one vote for each share held on all matters submitted to a vote of stockholders, and do not have cumulative voting rights. The common stock votes together as a single class. Directors will be elected by a plurality of the votes of the shares of common stock present in person or by proxy at a meeting of stockholders and voting for nominees in the election of directors. Except as otherwise provided in our Certificate of Incorporation or required by law, all matters to be voted on by our stockholders must be approved by a majority of the shares present in person or by proxy at a meeting of stockholders and entitled to vote on the subject matter.

Dividend Rights

Holders of common stock are entitled to receive proportionately any dividends as may be declared by our board of directors, subject to any preferential dividend rights of outstanding preferred stock.

Liquidation Rights

Upon our liquidation, dissolution or winding up, the holders of common stock are entitled to receive proportionately our net assets available after the payment of all debts and other liabilities and subject to the prior rights of any outstanding preferred stock.

Other Rights

Holders of common stock have no preemptive, subscription, redemption or other conversion rights and do not have any sinking fund provisions. The rights, preferences and privileges of holders of common stock are subject to, and may be adversely affected by, the rights of the holders of shares of any series of preferred stock which we may designate and issue in the future.

Shares of our common stock are not convertible into any other shares of our capital stock.

Preferred Stock

As of the date of this prospectus, there were no shares of our preferred stock outstanding.

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Pursuant to our Certificate of Incorporation, our board of directors has the authority, without further action by the stockholders (unless such stockholder action is required by applicable law or stock exchange listing rules), to designate and issue up to 10,000,000 shares of preferred stock in one or more series, to establish from time to time the number of shares to be included in each such series, to fix the designations, powers, preferences, privileges and relative participating, optional or special rights and the qualifications, limitations or restrictions thereof, including dividend rights, conversion rights, voting rights, terms of redemption and liquidation preferences, any or all of which may be greater than the rights of the common stock, and to increase or decrease the number of shares of any such series, but not below the number of shares of such series then outstanding.

The board of directors, without stockholder approval, can issue preferred stock with conversion or other rights that could adversely affect the voting power and other rights of the holders of common stock. Preferred stock could be issued quickly with terms designed to delay or prevent a change in control of our company or make removal of management more difficult. Additionally, the issuance of preferred stock may have the effect of decreasing the market price of the common stock and may adversely affect the voting power of holders of common stock and reduce the likelihood that common stockholders will receive dividend payments and payments upon liquidation.

Our board of directors will fix the designations, preferences and rights of each series, as well as the qualifications, limitations or restrictions thereof, of the preferred stock of each series that we offer under this prospectus and applicable prospectus supplements in the certificate of designation relating to that series. We will file as an exhibit to the registration statement of which this prospectus is a part, or will incorporate by reference from reports that we file with the SEC, the form of any certificate of designation that describes the terms of the series of preferred stock we are offering before the issuance of that series of preferred stock. This description will include:

• the title and stated value;

• the number of shares we are offering;

• the liquidation preference per share;

• the purchase price per share;

• the dividend rate per share, dividend period and payment dates and method of calculation for dividends;

• whether dividends will be cumulative or non-cumulative and, if cumulative, the date from which dividends will accumulate;

• our right, if any, to defer payment of dividends and the maximum length of any such deferral period;

• the procedures for any auction and remarketing, if any;

• the provisions for a sinking fund, if any;

• the provisions for redemption or repurchase, if applicable, and any restrictions on our ability to exercise those redemption and repurchase rights;

• the listing of the preferred stock on any securities exchange or market, if any;

• whether the preferred stock will be convertible into our common stock or other securities of ours, including depositary shares and warrants, and, if applicable, the conversion period, the conversion price, or how it will be calculated, and under what circumstances it may be adjusted;

• voting rights, if any, of the preferred stock;

• preemption rights, if any;

• restrictions on transfer, sale or other assignment, if any;

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• whether interests in the preferred stock will be represented by depositary shares;

• a discussion of any material or special United States federal income tax considerations applicable to the preferred stock;

• the relative ranking and preferences of the preferred stock as to dividend rights and rights if we liquidate, dissolve or wind up our affairs;

• any limitations on issuances of any class or series of preferred stock ranking senior to or on a parity with the series of preferred stock being issued as to dividend rights and rights if we liquidate, dissolve or wind up our affairs; and

• any other specific terms, rights, preferences, privileges, qualifications or restrictions of the preferred stock.

Qualifications for Ownership

The Company is subject to regulation under the Jones Act and related U.S. cabotage laws, which restrict ownership and operation of vessels in the U.S. coastwise trade (i.e., trade between points in the United States), including the transportation of cargo. Subject to limited exceptions, the Jones Act requires that vessels engaged in U.S. coastwise trade be built in the United States, registered under the U.S. flag, manned by predominantly U.S. crews, and owned and operated by U.S. citizens within the meaning of the Jones Act. Violation of the Jones Act could prohibit operation of vessels in the U.S. coastwise trade during the period of such non-compliance, result in material fines and subject Company vessels to seizure and forfeiture.

To facilitate compliance with the Jones Act, the Company’s Certificate of Incorporation and Bylaws: (i) limit (a) the aggregate percentage ownership by non-U.S. citizens of any class of the Company’s capital stock (including common stock) to 22.5% of the outstanding shares of each such class to ensure that ownership by non-U.S. citizens will not exceed the maximum percentage permitted by applicable maritime law (presently 25%) but authorize the Company’s board of directors, under certain circumstances, to increase the foregoing percentage to not more than 24% and (b) ownership of shares of any class or series of its capital stock by a single non-U.S. citizen (and any other non-U.S. citizen whose ownership position would be aggregated with such non-U.S. citizen for purposes of the Jones Act) to not more than the Permitted Percentage; (ii) allow for the institution of a dual stock certification system to help determine such ownership; (iii) provide that any issuance or transfer of shares in excess of the Permitted Percentage shall be ineffective as against the Company and that neither the Company nor its transfer agent shall register such purported issuance or transfer of shares or be required to recognize the purported transferee or owner as a stockholder of the Company for any purpose whatsoever except to exercise the Company’s remedies under the Certificate of Incorporation; (iv) provide that any excess shares above the Permitted Percentage shall not have any voting or dividend rights; (v) permit the Company to redeem or transfer to a charitable trust any such excess shares; and (vi) permit the board of directors to make such reasonable determinations as may be necessary to ascertain such ownership and implement such limitations. In addition, the Company’s Bylaws provide (w) that the number of non-U.S. citizen directors shall not exceed a minority of the number necessary to constitute a quorum for the transaction of business, (x) for an increase in the number of directors necessary to constitute a quorum when the number of non-U.S. citizen directors is equal to or greater than 50% of the number of directors present at a meeting, (y) that the President and the Chief Executive Officer of the Company must be a U.S. citizen and (z) that any non-U.S. citizen officer is restricted from acting in the absence or disability of the chairman of the board of directors, the Chief Executive Officer or the President.

Delaware Anti-Takeover Law and Provisions of Our Certificate of Incorporation and Bylaws

Section 203 of the Delaware General Corporate Law.

We are subject to the provisions of Section 203 of the Delaware General Corporation Law (“Section 203”). In general, Section 203 prohibits a publicly held Delaware corporation from engaging in a “business

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combination” with an “interested stockholder” for a three-year period following the time that this stockholder becomes an interested stockholder, unless the business combination is approved in a prescribed manner. A “business combination” includes, among other things, a merger, asset or stock sale or other transaction resulting in a financial benefit to the interested stockholder. An “interested stockholder” is a person who owns 15% or more of the corporation’s outstanding stock, or an affiliate or associate of the corporation who did own 15% or more of the corporation’s voting stock within three years prior to the determination of interested stockholder status. Under Section 203, a business combination between a corporation and an interested stockholder is prohibited unless it satisfies one of the following conditions:

• before the stockholder became interested, the board of directors approved either the business combination or the transaction which resulted in the stockholder becoming an interested stockholder;

• upon consummation of the transaction which resulted in the stockholder becoming an interested stockholder, the interested stockholder owned at least 85% of the voting stock of the corporation outstanding at the time the transaction commenced, excluding for purposes of determining the voting stock outstanding, shares owned by persons who are directors and also officers, and employee stock plans, in some instances; or

• at or after the time the stockholder became interested, the business combination was approved by the board of directors of the corporation and authorized at an annual or special meeting of the stockholders by the affirmative vote of at least two-thirds of the outstanding voting stock which is not owned by the interested stockholder.

A Delaware corporation may opt out of Section 203 either with an express provision in its original certificate of incorporation or in an amendment to its certificate of incorporation or bylaws approved by its stockholders. However, we have not opted out, and do not currently intend to opt out, of this provision. The statute could prohibit or delay mergers or other takeover or change in control attempts and, accordingly, may discourage attempts to acquire us.

Certificate of Incorporation and Bylaws.

Our Certificate of Incorporation and Bylaws contain provisions that may delay, defer or discourage another party from acquiring control of us. These provisions, which are summarized below, discourage coercive takeover practices or inadequate takeover bids. These provisions are designed to encourage persons seeking to acquire control of us to first negotiate with our board of directors, which we believe may result in an improvement of the terms of any such acquisition in favor of our stockholders. However, they also give our board of directors the power to discourage acquisitions that some stockholders may favor.

Filling Vacancies on the Board of Directors.

In accordance with Article II, Section 12 of our Bylaws, any vacancy on our board of directors, however occurring, including a vacancy resulting from an increase in the size of our board of directors, may only be filled by the affirmative vote of a majority of our directors then in office even if less than a quorum. Any director appointed to fill a vacancy will hold office until the next election of directors or until their successors are duly elected and qualified.

Meetings of Stockholders.

Our Bylaws provide that only a majority of the members of our board of directors then in office or the Chairman of the board of directors or the President may call special meetings of the stockholders and only those matters set forth in the notice of the special meeting may be considered or acted upon at a special meeting of stockholders. Our Bylaws limit the business that may be conducted at an annual meeting of stockholders to those matters properly brought before the meeting.

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Advance Notice Requirements.

Our Bylaws establish an advance notice procedure for stockholders to make nominations of candidates for election as directors or to bring other business before an annual meeting of our stockholders. The Bylaws provide that any stockholder wishing to nominate persons for election as directors at, or bring other business before, an annual meeting must deliver to our secretary a written notice of the stockholder’s intention to do so. To be timely, the stockholder’s notice must be delivered to us not later than the 120th day nor earlier than the 150th day prior to the anniversary date of the preceding annual meeting. If there was no such prior annual meeting, then a stockholder’s notice must be delivered not earlier than the close of business on the 150th day nor later than the 120th day prior to the date which represents the second Tuesday in May of the current year. In the event that the date of the annual meeting is more than 25 days before or after such anniversary date, then, to be considered timely, notice by the stockholders must be received not later than the close of business on the 10th day following the date on which public announcement of the date of such meeting is first made by us.

Transfer Agent and Registrar

The transfer agent and registrar for our common stock is Equiniti Trust Company, LLC, 48 Wall Street, New York, NY 10005.

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DESCRIPTION OF WARRANTS

We may issue warrants for the purchase of common stock or preferred stock in one or more series. We may issue warrants independently or together with common stock or preferred stock, if applicable, and such warrants may be attached to or separate from our common stock or preferred stock, as applicable. While the terms summarized below will apply generally to any warrants that we may offer, we will describe the particular terms of any series of warrants in more detail in the applicable prospectus supplement. The terms of any warrants offered under a prospectus supplement may differ from the terms described below.

We will file as exhibits to the registration statement of which this prospectus is a part, or will incorporate by reference from reports that we file with the SEC, the form of warrant agreement, including a form of warrant certificate, that describes the terms of the particular series of warrants we are offering before the issuance of the related series of warrants. The following summaries of material provisions of the warrants and the warrant agreements are subject to, and qualified in their entirety by reference to, all the provisions of the warrant agreement and warrant certificate applicable to the particular series of warrants that we may offer under this prospectus. We urge you to read the applicable prospectus supplements related to the particular series of warrants that we may offer under this prospectus, as well as any related free writing prospectuses, and the complete warrant agreements and warrant certificates that contain the terms of the warrants.

General

We will describe in the applicable prospectus supplement the terms of the series of warrants being offered, including:

• the offering price and aggregate number of warrants offered;

• the currency for which the warrants may be purchased;

• if applicable, the designation and terms of the securities with which the warrants are issued and the number of warrants issued with each such security or each principal amount of such security;

• limits on the ability to exercise the warrant including to ensure, among other things, compliance with the Jones Act and provisions of the Company’s Certificate of Incorporation and Bylaws;

• the number of shares of common stock or the number of shares of preferred stock purchasable upon the exercise of one warrant and the price at which such shares of common stock or shares of preferred stock may be purchased upon such exercise;

• the effect of any merger, consolidation, sale or other disposition of our business on the warrant agreements and the warrants;

• the terms of any rights to redeem or call the warrants;

• any provisions for changes to or adjustments in the exercise price or number of securities issuable upon exercise of warrants;

• the dates on which the right to exercise the warrants will commence and expire;

• the manner in which the warrant agreements and warrants may be modified;

• a discussion of any material or special United States federal income tax consequences of holding or exercising the warrants;

• the terms of the securities issuable upon exercise of warrants; and

• any other specific terms, preferences, rights or limitations of or restrictions on the warrants.

Before exercising their warrants, holders of warrants will not have any of the rights of holders of the securities purchasable upon such exercise, including the right to receive dividends, if any, or payments upon our liquidation, dissolution or winding up or to exercise voting rights, if any.

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Exercise of Warrants

Each warrant will entitle the holder to purchase the securities that we specify in the applicable prospectus supplement at the exercise price that we describe in the applicable prospectus supplement. Unless we otherwise specify in the applicable prospectus supplement, holders of the warrants may exercise the warrants at any time up to the specified time on the expiration date that we set forth in the applicable prospectus supplement subject to Jones Act restrictions and the Company’s Certificate of Incorporation and Bylaws. After the close of business on the expiration date, unexercised warrants will become void.

Holders of the warrants may exercise the warrants by delivering the warrant certificate representing the warrants to be exercised together with specified information and paying any required amount to the warrant agent in immediately available funds, as provided in the applicable prospectus supplement. We will set forth on the reverse side of the warrant certificate and in the applicable prospectus supplement the information that the holder of the warrant will be required to deliver to the warrant agent.

Upon receipt of the required payment and the warrant certificate properly completed and duly executed at the corporate trust office of the warrant agent or any other office indicated in the applicable prospectus supplement, we will issue and deliver the securities purchasable upon such exercise. If fewer than all of the warrants represented by the warrant certificate are exercised, then we will issue a new warrant certificate for the remaining number of warrants. If we so indicate in the applicable prospectus supplement, holders of the warrants may surrender securities as all or part of the exercise price for warrants.

Governing Law

Unless we provide otherwise in the applicable prospectus supplement, the warrants and warrant agreements will be governed by and construed in accordance with the laws of the State of New York.

Enforceability of Rights by Holders of Warrants

Each warrant agent will act solely as our agent under the applicable warrant agreement and will not assume any obligation or relationship of agency or trust with any holder of any warrant. A single bank or trust company may act as warrant agent for more than one issue of warrants. A warrant agent will have no duty or responsibility in case of any default by us under the applicable warrant agreement or warrant, including any duty or responsibility to initiate any proceedings at law or otherwise, or to make any demand upon us. Any holder of a warrant may, without the consent of the related warrant agent or the holder of any other warrant, enforce by appropriate legal action its right to exercise, and receive the securities purchasable upon exercise of, its warrants.

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DESCRIPTION OF UNITS

We may issue, in one or more series, units consisting of common stock, preferred stock and/or warrants for the purchase of common stock or preferred stock in any combination. Each unit will be issued so that the holder of the unit is also the holder of each security included in the unit. Thus, the holder of a unit will have the rights and obligations of a holder of each included security. The units may be issued under unit agreements to be entered into between us and a unit agent, as detailed in the prospectus supplement relating to the units being offered. The prospectus supplement will describe:

• the designation and terms of the units and of the securities comprising the units, including whether and under what circumstances the securities comprising the units may be held or transferred separately;

• a description of the terms of any unit agreement governing the units;

• a description of the provisions for the payment, settlement, transfer or exchange of the units; and

• whether the units if issued as a separate security will be issued in fully registered or global form.

While the terms summarized above will apply generally to any units that we may offer, we will describe the particular terms of any series of units in more detail in the applicable prospectus supplement. The terms of any units offered under a prospectus supplement may differ from the terms described above. We will file as exhibits to the registration statement of which this prospectus is a part, or will incorporate by reference from reports that we file with the SEC, any form of unit agreement, including any related agreements or certificates, that describes the terms of the particular series of units we are offering before the issuance of the related series of units. The material provisions of the units and any unit agreements are subject to, and qualified in their entirety by reference to, all the provisions of the unit agreement and related agreements and certificates applicable to the particular series of units that we may offer under this prospectus. We urge you to read the applicable prospectus supplements related to the particular series of units that we may offer under this prospectus, as well as any related free writing prospectuses, and the complete unit agreements and related agreements and certificates that contain the terms of the units.

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LEGAL MATTERS

The validity of the securities being offered by this prospectus will be passed upon by Milbank LLP, New York, New York. Additional legal matters may be passed upon for us or any underwriters, dealers or agents, by counsel that we will name in the applicable prospectus supplement.

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EXPERTS

The audited financial statements incorporated by reference in this prospectus and elsewhere in the registration statement have been so incorporated by reference in reliance upon the reports of Grant Thornton LLP, independent registered public accountants, upon the authority of said firm as experts in accounting and auditing.

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WHERE YOU CAN FIND ADDITIONAL INFORMATION

This prospectus is part of a registration statement that we have filed with the SEC. Certain information in the registration statement has been omitted from this prospectus in accordance with the rules of the SEC. We are a public company and file proxy statements, annual, quarterly and special reports and other information with the SEC. The SEC maintains a website at http://www.sec.gov that contains reports, proxy and information statements and other information regarding us and other issuers that file electronically with the SEC. We have also filed exhibits and schedules with the registration statement that are excluded from this prospectus, and you should refer to the applicable exhibit or schedule for a complete description of any statement referring to any contract or other document. You may access the registration statement of which this prospectus forms a part by visiting http://www.sec.gov.

We also maintain a website at https://seacormarine.com, through which you can access the Company’s SEC filings free of charge. The information set forth on our website is not part of this prospectus. The reference to our website address does not constitute incorporation by reference of the information contained on our website.

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INCORPORATION OF CERTAIN INFORMATION BY REFERENCE

We are incorporating by reference in this prospectus the documents that we file with the SEC. This means that we are disclosing important information to you by referring to these filings. The information we incorporate by reference is considered a part of this prospectus, and subsequent information that we file with the SEC will automatically update and supersede this information.

Any statement contained in a document incorporated or considered to be incorporated by reference in this prospectus shall be considered to be modified or superseded for purposes of this prospectus to the extent that a statement contained in this prospectus or in any other subsequently filed document that is considered to be incorporated by reference in this prospectus modifies or supersedes such statement.

We incorporate by reference the following documents that we have filed with the SEC:

• Annual Report on Form 10-K for the fiscal year ended December 31, 2023, filed on February 29, 2024;

• The information specifically incorporated by reference into our Annual Report on Form 10-K for the fiscal year ended December  31, 2023 from our definitive proxy statement on Schedule 14A (other than information furnished, rather than filed), filed on April 18, 2024;

• Quarterly Reports on Form 10-Q for the quarters ended March 31, 2024, filed on May 1, 2024, June  30, 2024, filed on July 31, 2024, and September  30, 2024, filed on October 30, 2024;

• Current Reports on Form 8-K (other than information furnished, rather than filed) filed with the SEC on March  5, 2024, June  6, 2024, September  19, 2024, and December 2, 2024; and

• The description of our capital stock included in our Form 10 filed on December 14, 2016 and the amendments thereto filed on February  10, 2017, April  28, 2017, and May 4, 2017, as described in Exhibit 4.2 to the registration statement of which this prospectus forms a part.

In addition, we incorporate by reference into this prospectus (i) all documents filed by us pursuant to Section 13(a), 13(c), 14 or 15(d) of the Exchange Act subsequent to the date of this prospectus and before we have sold all of the common stock to which the prospectus relates or the offering is otherwise terminated and (ii) all documents filed by us pursuant to the Exchange Act after the date of the initial registration statement and prior to effectiveness of the registration statement.

You may access our Annual Report on Form 10-K, Quarterly Reports on Form 10-Q, Current Reports on Form 8-K and amendments to any of these reports, free of charge on the SEC’s website. You may also access the documents incorporated by reference on our website at www.seacormarine.com. Other than the foregoing documents incorporated by reference, the information contained in, or that can be accessed through, our website is not part of this prospectus.

We will provide without charge to each person, including any beneficial owner, to whom a copy of this prospectus is delivered, upon written or oral request, a copy of any or all of the information that has been incorporated in this prospectus by reference but not delivered with this prospectus. You may obtain such documents by submitting a written request either to Investor Relations, SEACOR Marine Holdings Inc., 12121 Wickchester Lane, Suite 500, Houston, Texas 77079 or to InvestorRelations@seacormarine.com, or an oral request by calling the Company’s Investor Relations group at (346) 980-1700.

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$200,000,000

SEACOR MARINE HOLDINGS INC.

Common Stock

Preferred Stock

Warrants

Units

PROSPECTUS

    , 2025

The information in this prospectus is not complete and may be changed. We may not sell these securities or accept an offer to buy these securities until the registration statement filed with the Securities and Exchange Commission is effective. This prospectus is not an offer to sell these securities, and it is not soliciting offers to buy these securities in any jurisdiction where such offer or sale is not permitted.

SUBJECT TO COMPLETION, DATED FEBRUARY 7, 2025

PROSPECTUS

SEACOR MARINE HOLDINGS INC.

Up to $25,000,000

of Common Stock

We entered into an At Market Issuance Sales Agreement (the “sales agreement”) dated February 7, 2025, with B. Riley Securities, Inc. (the “sales agent”), as our sales agent, relating to shares of our common stock, par value $0.01 per share. In accordance with the terms of the sales agreement, we may offer and sell shares of our common stock having an aggregate offering price of up to $25,000,000 from time to time through or to our sales agent under this prospectus, as sales agent or as principal.

Sales of our common stock, if any, under this prospectus will be made by any method that is deemed to be an “at the market offering” as defined in Rule 415(a)(4) under the Securities Act of 1933, as amended (the “Securities Act”). Our common stock is listed on The New York Stock Exchange (“NYSE”) under the symbol “SMHI.” The last reported sale price of our common stock on The NYSE on February 3, 2025 was $6.79 per share.

The compensation of our sales agent for sales of common stock pursuant to the sales agreement shall be a commission rate up to 3.0% of the gross proceeds from each sale. The net proceeds from any sale under this prospectus will be used as described under “Use of Proceeds” in this prospectus. There is no arrangement for funds to be received in escrow, trust or similar arrangement.

In connection with the sale of the common stock on our behalf, the sales agent will be deemed to be an “underwriter” within the meaning of the Securities Act, and the compensation of the sales agent will be deemed to be underwriting commissions or discounts. We have also agreed to provide indemnification and contribution to the sales agent with respect to certain civil liabilities, including liabilities under the Securities Act. See “Plan of Distribution.”

The sales agent is not required to sell any specific number or dollar amount of common stock but will use its commercially reasonable efforts, as our agent and subject to the terms of the sales agreement, to sell the common stock offered, as instructed by us. The offering of common stock pursuant to this prospectus will terminate upon the earlier of (i) the sale of all common stock subject to this prospectus or (ii) the termination of the sales agreement by us or by the sales agent pursuant to the terms of the sales agreement. In addition, the sales agreement replaces the At Market Issuance Sales Agreement dated November 1, 2023 by and between the Company and the sales agent, which is being terminated in connection with the execution of the sales agreement.

Investing in our common stock involves a high degree of risk. See “Risk Factors” beginning on page 3 of this prospectus and the “Risk Factors” section contained in our reports filed with the Securities and Exchange Commission which are incorporated by reference herein for a discussion of information that should be considered in connection with an investment in our common stock.

Neither the Securities and Exchange Commission nor any state securities commission has approved or disapproved of these securities or determined if this prospectus is truthful or complete. Any representation to the contrary is a criminal offense.

B. Riley Securities

The date of this prospectus is February  , 2025.

TABLE OF CONTENTS

About This Prospectus	1
Prospectus Summary	1
The Offering	2
Risk Factors	3
Forward-Looking Statements	6
Use of Proceeds	9
Description of Common Stock	10
Plan of Distribution	13
Legal Matters	15
Experts	15
Incorporation of Certain Documents by Reference	16
Where You Can Find More Information	17

PROSPECTUS SUMMARY

This summary highlights certain information about us, this offering and information appearing elsewhere in this prospectus, and in the documents we incorporate by reference. This summary is not complete and does not contain all of the information that you should consider before investing in our securities. To fully understand this offering and its consequences to you, you should read this entire prospectus carefully, including the information referred to under the heading “Risk Factors” in this prospectus on page 4 and the “Risk Factors” section contained in our most recent Annual Report on Form 10-K, as updated by our subsequent filings under the Securities Exchange Act of 1934, as amended (the “Exchange Act”), and the financial statements and other information incorporated by reference in this prospectus when making an investment decision. In this prospectus, the terms “we,” “us,” and the “Company” refer to SEACOR Marine Holdings Inc. and its subsidiaries.

Our Company

The Company provides global marine and support transportation services to offshore energy facilities worldwide. As of September 30, 2024, the Company operated a diverse fleet of 55 support vessels, of which 54 were owned or leased-in and one was managed on behalf of an unaffiliated third party. The primary users of the Company’s services are major integrated national and international oil companies, independent oil and natural gas exploration and production companies, oil field service and construction companies, as well as offshore wind farm operators and offshore wind farm installation and maintenance companies.

The Company operates and manages a diverse fleet of offshore support vessels that (i) deliver cargo and personnel to offshore installations, including offshore wind farms, (ii) assist offshore operations for production and storage facilities, (iii) provide construction, well work-over, offshore wind farm installation and decommissioning support, (iv) carry and launch equipment used underwater in drilling and well installation, maintenance, inspection and repair and (v) handle anchors and mooring equipment for offshore rigs and platforms. Additionally, the Company’s vessels provide emergency response services and accommodations for technicians and specialists.

The Company operates its fleet in four principal geographic regions: the United States (“U.S.”), primarily in the Gulf of Mexico; Africa and Europe; the Middle East and Asia; and Latin America, primarily in Mexico and Guyana. The Company’s vessels are highly mobile and regularly and routinely move between countries within a geographic region. In addition, the Company’s vessels are redeployed among geographic regions, subject to flag restrictions, as changes in market conditions dictate. The number and type of vessels operated, their rates per day worked and their utilization levels are the key determinants of the Company’s operating results and cash flows.

Our principal executive offices are located at 12121 Wickchester Lane, Suite 500, Houston, Texas 77079. Our telephone number is (346) 980-1700. SEACOR Marine’s website address is www.seacormarine.com. Information contained on SEACOR Marine’s website is not and should not be deemed a part of this prospectus or any report or filing filed with or furnished to the SEC.

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THE OFFERING

Common stock offered by us Shares of common stock having an aggregate offering price of up to $25,000,000. The actual number of shares outstanding after this offering will vary depending on the number of shares sold and issued and the sales price of such shares.

Plan of distribution “At the market offering” that may be made from time to time to or through B. Riley Securities, Inc., as sales agent or principal. See “Plan of Distribution” in this prospectus.

Common stock to be outstanding after this offering, assuming an offering price of $6.79 per share⁽¹⁾ Up to 31,351,246 shares, assuming sales of 3,681,885 shares of our common stock in this offering at an offering price at a price of $6.79 per share, which was the closing price of our common stock on the NYSE on February 3, 2025. The actual number of shares issued will vary depending on the sales price under this offering.

Use of proceeds We intend to use the net proceeds from this offering for general corporate purposes, which may include working capital needs, capital expenditures, repayment or refinancing of indebtedness, acquisitions, stock repurchases and redemptions of securities. See “Use of Proceeds.”

Risk factors Investing in our common stock involves a high degree of risk. You should carefully consider all of the information in this prospectus and the documents incorporated by reference in this prospectus. In particular, see “Risk Factors” beginning on page 3 of this prospectus.

NYSE symbol “SMHI”

(1) The common stock outstanding after the offering is based on approximately 27,669,361 shares of our common stock outstanding as of January 31, 2025 and the sale of 3,681,885 shares of our common stock at an assumed offering price of $6.79 per share, the last reported sale price of our common stock on the NYSE on February 3, 2025, and excludes 2,561,603 shares of our common stock reserved for future issuance under our 2017 Equity Incentive Plan, 2020 Equity Incentive Plan, and 2022 Equity Incentive Plan as of January 31, 2025 or underlying options or performance restricted stock units currently issued and outstanding under such plans.

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RISK FACTORS

Investing in our common stock involves substantial risk. You should carefully consider the risk factors disclosed below as well as those contained in our most recent Annual Report on Form 10-K, which is incorporated by reference herein, as updated by our subsequent filings under the Exchange Act, and the other information contained in this prospectus before acquiring any of our common stock. These risks could have a material adverse effect on our business, results of operations or financial condition and cause the value of our common stock to decline. You could lose all or part of your investment.

This prospectus also contains or incorporates by reference forward-looking statements that involve risks and uncertainties. Our actual results could differ materially from those anticipated in the forward-looking statements as a result of certain factors, including the risks faced by us described or incorporated by reference in this prospectus. See “Forward-Looking Statements.”

Risks Related to our Common Stock and the Offering

Our management will have broad discretion as to the use of proceeds from this offering and we may not use the proceeds effectively.

Our management will have broad discretion in the application of the net proceeds from this offering, if any, and could spend the proceeds in ways that do not improve our results of operations or enhance the value of our common stock. You will be relying on the judgment of our management concerning these uses and you will not have the opportunity, as part of your investment decision, to assess whether the proceeds are being used appropriately. The failure of our management to apply these funds effectively could result in unfavorable returns and uncertainty about our prospects, each of which could cause the price of our common stock to decline.

There may be future dilution of our common stock as a result of future sales of our common stock, which could adversely impact our stock price.

The issuance of shares of our common stock from time to time pursuant to the sales agreement may have a dilutive effect on our earnings per share, which could adversely impact the market price of our common stock. The actual amount of dilution and the effect on the market price of our common stock, if any, will be based on numerous factors, particularly the actual number of shares issued pursuant to the sales agreement, the use of proceeds and the return generated by the investments acquired with the net proceeds, and cannot be determined at this time. In addition, the issuance and sale of substantial amounts of our common stock, or the perception that such issuances and sales may occur, could adversely affect the market price of our common stock and impair our ability to raise capital through the sale of additional equity securities. Additionally, the sale of shares of common stock in this offering will increase the supply of available shares, which may result in a decrease in the price of our common stock.

The shares of our common stock offered under this prospectus will be sold in “at the market offerings”, and investors who buy shares at different times will likely pay different prices.

Investors who purchase shares under this prospectus at different times will likely pay different prices, and so may experience different outcomes in their investment results. We will have discretion, subject to market demand, to vary the timing, prices, and numbers of shares sold, and to determine the minimum sales price for shares sold. Investors may experience declines in the value of their shares as a result of share sales made in connection with “at the market offerings” at prices lower than the prices they paid.

The actual number of shares we will issue under the sales agreement, at any one time or in total, is uncertain.

Subject to certain limitations in the sales agreement and compliance with applicable law, we and our sales agent may mutually agree to sell shares of our common stock under a placement notice at any time throughout

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the term of the sales agreement. The number of shares that are sold by our sales agent in connection with any placement notice will fluctuate based on the market price of the shares of our common stock during the sales period and limits we set with our sales agent. Because the price per share of each share sold will fluctuate based on the market price of our shares of common stock during the sales period, it is not possible to predict the number of shares that will ultimately be issued.

Our stock price may fluctuate significantly, and investors may not be able to sell their shares at an attractive price.

The trading price of our common stock may be volatile and subject to wide price fluctuations in response to various factors including:

• market conditions in the broader stock market;

• our capital structure and liquidity;

• commodity prices and in particular prices of oil and natural gas;

• actual or anticipated fluctuations in our quarterly financial condition and results of operations;

• introduction of new equipment or services by us or our competitors;

• issuance of new or changed securities analysts’ reports or recommendations;

• purchases and sales of large blocks of our common stock and the frequency and volume with which the common stock trades on the NYSE;

• additions or departures of key personnel;

• the ability or willingness of OPEC to set and maintain production levels for oil;

• oil and natural gas production levels by non-OPEC countries;

• regulatory or political developments;

• litigation and governmental investigations; and

• changing economic conditions, including economic changes in the shipping industry.

These and other factors may cause the market price and demand for our common stock to fluctuate substantially, which may limit or prevent investors from readily selling their shares of our common stock and may otherwise negatively affect the liquidity of our common stock. In addition, in the past, when the market price of a stock has been volatile, holders of that stock have sometimes instituted securities class action litigation against the company that issued the stock. If any of our stockholders were to bring a lawsuit against us, we could incur substantial costs defending the lawsuit. Such a lawsuit could also divert the time and attention of our management from our business.

An investor’s percentage of ownership in the Company may be diluted in the future.

As with any publicly traded company, an investor’s percentage ownership in the Company may be diluted in the future because of the issuance of additional common stock. From time to time, we have issued and we expect we will continue to issue stock options or restricted stock grants or similar awards to employees, officers, and directors pursuant to our equity incentive award plans. Investors in our equity securities may experience dilution as these awards vest and are exercised by their holders and as the restrictions lapse on the restricted stock grants. We also may issue common stock, preferred stock or warrants of the Company to purchase common stock or preferred stock to raise capital to fund our growth initiatives in connection with acquisitions or the settlement of obligations or indebtedness, which would result in further dilution of existing stockholders. The issuance of any such shares of common stock, preferred stock or warrants to purchase common stock or preferred stock may result in a reduction of the book value or market price of the outstanding shares of our common stock.

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Provisions in our certificate of incorporation and bylaws, and Delaware law, may discourage, delay or prevent a change of control of us or changes in our management and, therefore, may depress the trading price of our common stock.

Our Third Amended and Restated Certificate of Incorporation, dated June 11, 2019 (our “certificate of incorporation”) and Third Amended and Restated Bylaws, dated March 15, 2019 (our “bylaws”) include certain provisions that could have the effect of discouraging, delaying or preventing a change of control of us or changes in our management, including, among other things:

• restrictions on the ability of our stockholders to fill a vacancy on the Board of Directors;

• restrictions related to the ability of non-U.S. citizens owning our common stock;

• our ability to issue preferred stock with terms that the Board of Directors may determine, without stockholder approval, which could be used to significantly dilute the ownership of a hostile acquirer;

• the absence of cumulative voting in the election of directors which may limit the ability of minority stockholders to elect directors;

• limiting the ownership of non-U.S. citizens to 22.5%, which is lower than the Jones Act limitation of 25%; and

• advance notice requirements for stockholder proposals and nominations, which may discourage or deter a potential acquirer from soliciting proxies to elect a particular slate of directors or otherwise attempting to obtain control of us.

These provisions in our certificate of incorporation and bylaws may discourage, delay or prevent a transaction involving a change in control of us that is in the best interests of our stockholders. Even in the absence of a takeover attempt, the existence of these provisions may adversely affect the prevailing market price of our common stock if they are viewed as discouraging future takeover attempts.

We do not expect to pay dividends to holders of our common stock.

We currently intend to retain our future earnings, if any, for the foreseeable future, to repay indebtedness and to fund the development and growth of our business. We do not intend to pay any dividends to holders of our common stock. As a result, capital appreciation in the price of our common stock, if any, will be investors’ only source of gain or income on an investment in our common stock.

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FORWARD-LOOKING STATEMENTS

The information discussed in this prospectus, our filings with the SEC and our public releases include “forward-looking statements” within the meaning of Section 27A of the Securities Act, as amended, and Section 21E of the Exchange Act, the Private Securities Litigation Reform Act of 1995 (the “PSLRA”), or in releases made by the SEC. Such forward-looking statements involve known and unknown risks, uncertainties and other important factors that could cause the actual results, performance or achievements of us to differ materially from any future results, performance or achievements expressed or implied by such forward-looking statements. Statements that are not historical fact are forward-looking statements. Forward-looking statements can be identified by, among other things, the use of forward-looking language, such as the words “plan,” “believe,” “expect,” “anticipate,” “intend,” “estimate,” “project,” “may,” “will,” “would,” “could,” “should,” “seeks,” or “scheduled to,” or other similar words, or the negative of these terms or other variations of these terms or comparable language, or by discussion of strategy or intentions. These cautionary statements are being made pursuant to the Securities Act, the Exchange Act and the PSLRA with the intention of obtaining the benefits of the “safe harbor” provisions of such laws.

The forward-looking statements contained in or incorporated by reference into this prospectus are largely based on our expectations, which reflect estimates and assumptions made by our management. These estimates and assumptions reflect our best judgment based on currently known market conditions and other factors. Although we believe such estimates and assumptions to be reasonable, they are inherently uncertain and involve a number of risks and uncertainties that are beyond our control, including:

• fluctuating prices and decreased demand for oil and natural gas;

• decreased demand for offshore oil and natural gas exploration, development and production;

• public health emergencies and their impact and disruption to business operations and workforce;

• restrictions and limitations imposed by credit facilities on operating and financial flexibility;

• indebtedness;

• downward pricing pressures on the price of crude oil and natural gas resulting from unconventional crude oil and natural gas sources and improved economics of producing natural gas and oil from such sources;

• losses or impairment charges related to sold or idle vessels;

• increase in competition in the offshore marine service industry;

• oversupply of vessels or equipment serving offshore oil and natural gas operations may adversely impact charter rates for vessels and equipment;

• loss of significant customers;

• consolidation of customer base may adversely affect demand for services and reduction in revenue;

• inability to maintain or replace offshore support vessels as they age;

• failure to successfully complete construction or conversion of vessels, repairs, maintenance or routine dry dockings on schedule and on budget;

• inability to attract and retain qualified personnel and crew vessels appropriately;

• inability to improve operations and financial systems, and recruitment of additional staff;

• seasonal factors and their impact on business operations and workforce;

• incurring high levels of fixed costs regardless of business activity levels;

• incurring higher than expected costs to return previously cold-stacked vessels to class as the markets recover or marketing strategies change;

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• inflation and increased interest rates may increase operating costs and capital costs;

• inability to renew or replace expiring contracts for vessels;

• early termination of vessel contracts may adversely affect operations;

• inability to protect against service interruptions, data corruption, cyber-based attacks or network security breaches;

• failure to comply with data protection and privacy laws could lead to financial penalties and reputational harm;

• increased domestic and international laws and regulations, including additional laws and regulations in the event of high-profile incidents;

• changes in federal government regulation of offshore resources for the production of oil and natural gas;

• changes in laws and regulations, including environmental laws and regulations that can adversely affect the cost, manner or feasibility of doing business;

• global climate change and changes to environmental regulations and environmental expectations;

• instability of political, military and economic conditions in foreign countries;

• business operation disruptions and exposure to liability caused by hazards inherent to the operation of vessels;

• ability to retain customers due to a failure to maintain an acceptable safety record;

• inadequacy of insurance coverage;

• inadequate indemnification by customers for damage to their property or the property of their other contractors;

• adverse effects and additional risks to business resulting from significant corporate transactions;

• prohibition of operation of offshore support vessels in the U.S. resulting from failure to restrict the amount of ownership of the Company’s common stock by non-U.S. citizens;

• repeal, amendment, suspension or non-enforcement of the Jones Act;

• inability to sell off a portion of the business or forfeiture of vessels resulting from restrictions placed on non-U.S. citizen ownership;

• restrictions placed by the Company’s incorporation and formation documents limiting ownership of common stock by individuals and entities that are not U.S. citizens may affect liquidity of common stock and may result in non-U.S. citizens being required to sell their shares at a loss or relinquish their voting, dividend and distribution rights;

• inability to access funds, redeem any excess shares and suspension of operations in the U.S. coastwise trade due to non-U.S. citizens owning more than 25% of the Company’s common stock;

• requisition or use by governmental agencies of the Company’s vessels;

• inability to improve cash flow and liquidity through vessel sales resulting from inability to locate buyers with access to financing or to complete any sales on acceptable terms or within a reasonable time frame;

• inability to collect amounts owed by customers;

• lack of sole decision-making authority and disputes between joint ventures and investments in joint ventures;

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• exposure to potential future losses due to participation in industry-wide, multi-employer, defined benefit pension plans;

• federal law and state law job-related claims;

• fluctuations in common stock price;

• ownership dilution;

• common stock price and trading volume decline due to securities or industry analyst reports and recommendations;

• costs associated with the development and maintenance of proper and effective internal controls over financial reporting;

• failure to achieve and maintain effective internal controls over financial reporting;

• depression of common stock price due to provisions in the Company’s incorporation and formation documents that may discourage, delay or prevent a change of control of the Company or changes in the Company’s management;

• limitations to common stockholders’ ability to obtain favorable judicial forum for disputes due to forum selection clause restrictions placed by the Company’s incorporation and formation documents; and

• intention not to pay dividends on our common stock for the foreseeable future.

Many of these factors are beyond our ability to control or predict. These factors are not intended to represent a complete list of the general or specific factors that may affect us.

In addition, management’s assumptions about future events may prove to be inaccurate. All readers are cautioned that the forward-looking statements contained in this prospectus and in the documents incorporated by reference into this prospectus are not guarantees of future performance, and we cannot assure any reader that such statements will be realized or that the forward-looking events and circumstances will occur. Actual results may differ materially from those anticipated or implied in the forward-looking statements due to factors described in “Risk Factors” included elsewhere in this prospectus and in the documents that we include in or incorporate by reference into this prospectus, including our Annual Report on Form 10-K for the fiscal year ended December 31, 2023, and our subsequent SEC filings. All forward-looking statements speak only as of the date they are made. We do not intend to update or revise any forward-looking statements as a result of new information, future events or otherwise, except as required by law. These cautionary statements qualify all forward-looking statements attributable to us or persons acting on our behalf.

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USE OF PROCEEDS

We may issue and sell shares of our common stock having aggregate gross sale proceeds of up to $25,000,000 from time to time.

There can be no assurance that we will be able to sell any shares under or fully utilize the sales agreement with the sales agent as a source of financing. Because there is no minimum offering amount required as a condition to close this offering, the actual total public offering amount, commissions and proceeds to us, if any, are not determinable at this time. We currently intend to use the net proceeds from this offering, after deducting the sales agent’s commissions and our offering expenses, for general corporate purposes such as, but not limited to, working capital, capital expenditures, repayment and refinancing of debt, acquisitions and stock repurchases. The amounts and timing of our use of proceeds will vary depending on many factors, including regulatory developments, the amount of cash generated or used by our operations, and the rate of growth, if any, of our business and other capital requirements. As a result, we will retain broad discretion in the allocation of the net proceeds, if any, we receive in connection with securities offered pursuant to this prospectus, and investors will be relying on the judgment of our management regarding the application of the proceeds.

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DESCRIPTION OF COMMON STOCK

The following description sets forth certain material terms and provisions of our common stock. The following description is a summary and does not purport to be complete. It is subject to, and qualified in its entirety by reference to, our certificate of incorporation and our bylaws, which are filed as Exhibit 10.1 to our Quarterly Report on Form 10-Q filed with the SEC on August 7, 2019 and Exhibit 3.1 to our Current Report on Form 8-K filed with the SEC on March 19, 2019, respectively, which are incorporated by reference herein. Please read “Where You Can Find More Information.”

Authorized and Outstanding Capital Stock

The following description of our common stock and provisions of our certificate of incorporation and bylaws are summaries and are qualified by reference to our certificate of incorporation and bylaws, which have been incorporated by reference herein.

Our authorized capital stock consists of 60,000,000 shares of common stock, par value $0.01 per share, and 10,000,000 shares of undesignated preferred stock, par value $0.01 per share.

As of January 31, 2025, there were 27,669,361 shares of common stock outstanding, and no shares of preferred stock outstanding.

Common Stock

The holders of our common stock are entitled to the following rights.

Voting Rights

Holders of our common stock are entitled to one vote for each share held on all matters submitted to a vote of stockholders, and do not have cumulative voting rights. The common stock votes together as a single class. Directors will be elected by a plurality of the votes of the shares of common stock present in person or by proxy at a meeting of stockholders and voting for nominees in the election of directors. Except as otherwise provided in our Certificate of Incorporation or required by law, all matters to be voted on by our stockholders must be approved by a majority of the shares present in person or by proxy at a meeting of stockholders and entitled to vote on the subject matter.

Dividend Rights

Holders of common stock are entitled to receive proportionately any dividends as may be declared by our board of directors, subject to any preferential dividend rights of outstanding preferred stock.

Liquidation Rights

Upon our liquidation, dissolution or winding-up, the holders of common stock are entitled to receive proportionately our net assets available after the payment of all debts and other liabilities and subject to the prior rights of any outstanding preferred stock.

Other Rights

Holders of common stock have no preemptive, subscription, redemption or other conversion rights and do not have any sinking fund provisions. The rights, preferences and privileges of holders of common stock are

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subject to, and may be adversely affected by, the rights of the holders of shares of any series of preferred stock which we may designate and issue in the future.

Shares of our common stock are not convertible into any other shares of our capital stock.

Our Certificate of Incorporation and Our Bylaws

General. Certain provisions of our certificate of incorporation and bylaws could make our acquisition by a third party, a change in our incumbent management, or a similar change of control more difficult. These provisions, which are summarized below, are likely to reduce our vulnerability to an unsolicited proposal for the restructuring or sale of all or substantially all of our assets or an unsolicited takeover attempt. The summary of the provisions set forth below does not purport to be complete and is qualified in its entirety by reference to our certificate of incorporation and our bylaws.

Preferred Stock. The authorization of undesignated preferred stock makes it possible for our Board of Directors to issue preferred stock with voting or other rights or preferences that could impede the success of any attempt to acquire control of the Company.

Action by Written Consent. Our certificate of incorporation provides that any action required or permitted to be taken at a meeting of the stockholders may be taken by written consent if, but only if, a consent or consents in writing, setting forth the action so taken, are signed by the holders of not less than a majority (or such greater amount as may then be required by applicable law) in voting power of the outstanding shares of common stock entitled to vote thereon.

Advance Notice Requirements. Stockholders wishing to nominate persons for election to our Board of Directors at a meeting or to propose any business to be considered by our stockholders at a meeting must comply with certain advance notice and other requirements set forth in our bylaws.

Special Meetings. Our bylaws provide that special meetings of stockholders may only be called by order of a majority of the entire Board of Directors or by the Chairman of the Board or by the President of the Company.

Board Vacancies. Our bylaws provide that any vacancy on our Board of Directors may be filled by the Board of Directors or the Chairman of the Board; provided, however, that (a) the Chairman of the Board shall not have the power to fill a vacancy occurring in the office of any officer for whose election or appointment a provision is made in the bylaws stating that such officer shall be chosen solely by the Board of Directors and (b) prior to filling any vacancy in respect of the office of the Chief Financial Officer, the Chairman of the Board shall consult with the Audit Committee of the Board of Directors.

Removal of Directors. Our bylaws provide that any directors may be removed either with or without cause at any time by an affirmative vote of a majority of the entire Board of Directors.

Amendment of Certificate of Incorporation and Bylaws

Our bylaws may be altered or repealed at the annual meeting of stockholders or at any special meeting of the stockholders, in each case, at which a quorum is present or represented, provided in the case of a special meeting that notice of the proposed alteration or repeal is contained in the notice of such special meeting, by the affirmative vote of the holders of a majority in voting power of the outstanding capital stock entitled to vote at such meeting and present or represented thereat (in person or by proxy), or by the affirmative vote of a majority of the Board of Directors, at any regular meeting or any special meeting of the Board.

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Limitation of Liability and Indemnification of Officers and Directors

Our certificate of incorporation limits the personal liability of directors and officers for breach of fiduciary duty to the Company or our stockholders. However, this provision does not eliminate or limit the liability of any of our directors and officers:

• for any breach of the director’s duty of loyalty to the Company or its stockholders; or

• for acts or omissions which are not taken or omitted to be taken in good faith or which involve intentional misconduct or knowing violation of the law; or

• for any matter in respect of which such director would be liable under Section 174 of Title 8 of the Delaware General Corporation Law (“DGCL”) or any amendment or successor provision thereto; or

• for any transaction from which the director shall have derived an improper personal benefit.

Any repeal or modification of this provision will be prospective only and will not adversely affect any limitation on the personal liability of a director or officer of the Company for acts or omissions prior to such repeal or modification.

Our bylaws provide that the Company shall indemnify any director or officer of the Company against all costs and expenses actually and reasonably incurred by such person or on such person’s behalf, to the extent such director or officer is a party to or a witness in an action, suit or proceeding by reason of its position with the Company.

Authorized but Unissued Shares

Our authorized but unissued shares of common stock and preferred stock are available for future issuance, subject to any limitations imposed by the listing standards of the NYSE. These additional shares may be used for a variety of corporate finance transactions, acquisitions and employee benefit plans. The existence of authorized but unissued and unreserved common stock and preferred stock could make it more difficult or discourage an attempt to obtain control of us by means of a proxy contest, tender offer, merger or otherwise.

Transfer Agent and Registrar

The transfer agent and registrar for our common stock is Equiniti Trust Company, LLC. Its address is 48 Wall Street, New York, NY 10005 and its telephone number is 800-937-5449.

Our common stock is listed on the NYSE under the symbol “SMHI.”

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PLAN OF DISTRIBUTION

We have entered into an At Market Issuance Sales Agreement (the “sales agreement”) with B. Riley Securities, Inc. (the “sales agent”), as our sales agent, under which we may issue and sell shares of our common stock having an aggregate offering price of up to $25,000,000 from time to time through or to the sales agent as sales agent or principal. The sales agent may sell the common stock by any method that is deemed to be an “at the market offering” as defined in Rule 415 promulgated under the Securities Act.

Each time we wish to issue and sell common stock under the sales agreement, we will notify the sales agent of the number or dollar value of shares to be issued, the dates on which such sales are anticipated to be made, any limitation on the number of shares that may be sold in one day, any minimum price below which sales may not be made, and other sales parameters as we deem appropriate. Once we have so instructed the sales agent, unless the sales agent declines to accept the terms of such notice, it has agreed to use its commercially reasonable efforts consistent with its normal trading and sales practices to sell such shares up to the amount specified on such terms. The obligations of the sales agent under the sales agreement to sell our common stock are subject to a number of customary conditions that we must meet. We may instruct the sales agent not to sell our common stock if the sales cannot be effected at or above the price designated by us in any such instruction. We and the sales agent may suspend the offering of common stock upon proper notice to the other party and subject to other conditions. We and the sales agent each have the right, by giving written notice as specified in the sales agreement, to terminate the sales agreement in each party’s sole discretion at any time upon five days’ prior notice.

Under the terms of the sales agreement, we may also sell our common stock to the sales agent, as principal for its own account, at a price negotiated at the time of sale, provided that no sales may be made in a privately negotiated transaction without our prior consent.

Unless otherwise specified in the applicable placement notice, settlement for shares of our common stock will occur on the trading day following the date on which the sales are made. Sales of our common stock as contemplated in this prospectus will be settled through the facilities of The Depository Trust Company or by such other means as we and the sales agent may agree upon. There is no arrangement for funds to be received in an escrow, trust or similar arrangement.

We will pay the sales agent a commission for its services in acting as agent in the sale of common stock at a commission rate of up to 3.0% of the gross proceeds from each sale. We also agreed to reimburse the sales agent for certain specified fees and documented expenses, including the fees and documented expenses of its legal counsel in an amount not to exceed $35,000.00, plus an additional amount not to exceed $5,000.00 per fiscal quarter on an ongoing basis during the term of the sales agreement, as provided in the sales agreement. Because there is no minimum offering amount required as a condition to close this offering, the actual total public offering amount, commissions and proceeds to us, if any, are not determinable at this time. We estimate that the total expenses for the offering, excluding compensation payable to the sales agent and expense reimbursement under the terms of the sales agreement, will be up to approximately $200,000.

In addition, the sales agreement provides that we will not (i) take any action designed to cause or result in, or that constitutes or would reasonably be expected to constitute, the stabilization or manipulation of the price of any of our securities to facilitate the sale or resale of common stock, or (ii) sell, bid for, or purchase common stock in violation of Regulation M, or pay anyone any compensation for soliciting purchases of the common stock under the sales agreement other than the sales agent.

In connection with the sale of the common stock on our behalf, the sales agent will be deemed to be an “underwriter” within the meaning of the Securities Act as amended, and its compensation will be deemed to be underwriting commissions or discounts. We have agreed to provide indemnification and contribution to the sales agent with respect to certain liabilities, including civil liabilities under the Securities Act.

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The offering of our common stock pursuant to the sales agreement will terminate upon the earlier of (1) the issuance and sale of all common stock subject to the sales agreement; and (2) the termination of the sales agreement as described therein.

The sales agent and its affiliates have in the past and may in the future provide various investment banking and/or other financial services for us and/or our affiliates, for which services they may in the future receive customary fees. In addition, the sales agreement replaces the At Market Issuance Sales Agreement dated November 1, 2023 by and between the Company and the sales agent, which is being terminated in connection with the execution of the sales agreement. To the extent required by Regulation M under the Exchange Act, the sales agent will not engage in any market making activities involving our common stock while the offering is ongoing under this prospectus. This summary of the material provisions of the sales agreement does not purport to be a complete statement of its terms and conditions. A copy of the sales agreement is filed with the SEC as an exhibit to the registration statement of which this prospectus is a part. See “Where You Can Find More Information” below.

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LEGAL MATTERS

The validity of the shares of common stock offered by this prospectus were passed upon by Milbank LLP, New York, New York. Certain matters will be passed upon for the sales agent by Morgan, Lewis & Bockius LLP, Palo Alto, California.

EXPERTS

The audited financial statements incorporated by reference in this prospectus and elsewhere in the registration statement have been so incorporated by reference in reliance upon the reports of Grant Thornton LLP, independent registered public accountants, upon the authority of said firm as experts in accounting and auditing.

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INCORPORATION OF CERTAIN DOCUMENTS BY REFERENCE

We are incorporating by reference in this prospectus the documents that we file with the SEC. This means that we are disclosing important information to you by referring to these filings. The information we incorporate by reference is considered a part of this prospectus, and subsequent information that we file with the SEC will automatically update and supersede this information.

Any statement contained in a document incorporated or considered to be incorporated by reference in this prospectus shall be considered to be modified or superseded for purposes of this prospectus to the extent that a statement contained in this prospectus or in any other subsequently filed document that is considered to be incorporated by reference in this prospectus modifies or supersedes such statement.

We incorporate by reference the following documents that we have filed with the SEC:

• Annual Report on Form 10-K for the fiscal year ended December 31, 2023, filed on February 29, 2024;

• The information specifically incorporated by reference into our Annual Report on Form 10-K for the fiscal year ended December  31, 2023 from our definitive proxy statement on Schedule 14A (other than information furnished, rather than filed) filed on April 18, 2024;

• Quarterly Reports on Form 10-Q for the quarters ended March 31, 2024, filed on May 1, 2024, June  30, 2024, filed on July 31, 2024 and September  30, 2024, filed on October 30, 2024;

• Current Reports on Form 8-K (other than information furnished, rather than filed) filed with the SEC on March  5, 2024, June  6, 2024, September  19, 2024, and December 2, 2024; and

• The description of our capital stock included in our Form 10 filed on December 14, 2016 and the amendments thereto filed on February  10, 2017, April  28, 2017 and May 4, 2017, as described in Exhibit 4.2 to the registration statement of which this prospectus forms a part.

In addition, we incorporate by reference into this prospectus (i) all documents filed by us pursuant to Section 13(a), 13(c), 14 or 15(d) of the Exchange Act subsequent to the date of this prospectus and before we have sold all of the common stock to which the prospectus relates or the offering is otherwise terminated and (ii) all documents filed by us pursuant to the Exchange Act after the date of the initial registration statement and prior to effectiveness of the registration statement.

You may access our Annual Report on Form 10-K, Quarterly Reports on Form 10-Q, Current Reports on Form 8-K and amendments to any of these reports, free of charge on the SEC’s website. You may also access the documents incorporated by reference on our website at www.seacormarine.com. Other than the foregoing documents incorporated by reference, the information contained in, or that can be accessed through, our website is not part of this prospectus.

We will provide without charge to each person, including any beneficial owner, to whom a copy of this prospectus is delivered, upon written or oral request, a copy of any or all of the information that has been incorporated in this prospectus by reference but not delivered with this prospectus. You may obtain such documents by submitting a written request either to Investor Relations, SEACOR Marine Holdings Inc., 12121 Wickchester Lane, Suite 500, Houston, Texas 77079 or to InvestorRelations@seacormarine.com, or an oral request by calling the Company’s Investor Relations group at (346) 980-1700.

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WHERE YOU CAN FIND MORE INFORMATION

We are subject to the informational requirements of the Exchange Act and in accordance therewith, file reports, proxy statements and other information with the SEC. The SEC maintains an Internet site at www.sec.gov that contains reports, proxy and information statements, and other information regarding issuers that file electronically with the SEC. We maintain a website at www.seacormarine.com. Information on our website or any other website is not incorporated by reference into this prospectus and does not constitute part of this prospectus. Please note that information contained in our website, whether currently posted or posted in the future, is not a part of this prospectus or the documents incorporated by reference in this prospectus.

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PART II

INFORMATION NOT REQUIRED IN PROSPECTUS

Item 14. Other Expenses of Issuance and Distribution.

The following table sets forth the estimated costs and expenses, other than underwriting discounts and commissions, payable by us in connection with the offering of the securities being registered. All the amounts shown are estimates, except for the SEC registration fee.

SEC registration fee	$	30,620.00
Accounting fees and expenses			*
Legal fees and expenses			*
Transfer agent fees and expenses			*
Trustee fees and expenses			*
Printing and miscellaneous expenses			*
Total	$		*

* These fees are calculated based on the securities offered and the number of issuances and accordingly cannot be estimated at this time. The applicable prospectus supplement will set forth the aggregate amount of expenses payable in respect of any offering of securities.

Item 15. Indemnification of Directors and Officers.

Section 145 of the DGCL provides that a corporation may indemnify any person who was or is a party or is threatened to be made a party to any threatened, pending or completed action, suit or proceeding whether civil, criminal, administrative or investigative (other than an action by or in the right of the corporation) by reason of the fact that he is or was a director, officer, employee or agent of the corporation, or is or was serving at the request of the corporation as a director, officer, employee or agent of another corporation, partnership, joint venture, trust or other enterprise, against expenses (including attorneys’ fees), judgments, fines and amounts paid in settlement actually and reasonably incurred by him in connection with such action, suit or proceeding if he acted in good faith and in a manner he reasonably believed to be in or not opposed to the best interests of the corporation, and, with respect to any criminal action or proceeding, had no reasonable cause to believe his conduct was unlawful. Section 145 further provides that a corporation similarly may indemnify any such person serving in any such capacity who was or is a party or is threatened to be made a party to any threatened, pending or completed action or suit by or in the right of the corporation to procure a judgment in its favor by reason of the fact that he is or was a director, officer, employee or agent of the corporation or is or was serving at the request of the corporation as a director, officer, employee or agent of another corporation, partnership, joint venture, trust or other enterprise, against expenses (including attorney’s fees) actually and reasonably incurred in connection with the defense or settlement of such action or suit if he acted in good faith and in a manner he reasonably believed to be in or not opposed to the best interests of the corporation and except that no indemnification shall be made in respect of any claim, issue or matter as to which such person shall have been adjudged to be liable to the corporation unless and only to the extent that the Delaware Court of Chancery or such other court in which such action or suit was brought shall determine upon application that, despite the adjudication of liability but in view of all of the circumstances of the case, such person is fairly and reasonably entitled to indemnity for such expenses which the Delaware Court of Chancery or such other court shall deem proper.

The Bylaws authorize the indemnification of its officers and directors, consistent with Section 145 of the DGCL, as amended. The Company has entered into indemnification agreements with each of its directors and executive officers. These agreements, among other things, require us to indemnify each director and executive officer to the fullest extent permitted by Delaware law, including indemnification of expenses such as attorneys’ fees, judgments, fines and settlement amounts incurred by the director or executive officer in any action or

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proceeding, including any action or proceeding by or in right of us, arising out of the person’s services as a director or executive officer.

Reference is made to Section 102(b)(7) of the DGCL, which enables a corporation in its original certificate of incorporation or an amendment thereto to eliminate or limit the personal liability of a director for violations of the director’s fiduciary duty, except (i) for any breach of the director’s duty of loyalty to the corporation or its stockholders, (ii) for acts or omissions not in good faith or which involve intentional misconduct or a knowing violation of law, (iii) pursuant to Section 174 of the DGCL, which provides for liability of directors for unlawful payments of dividends of unlawful stock purchase or redemptions or (iv) for any transaction from which a director derived an improper personal benefit. The Certificate of Incorporation provides for such exculpation from personal liability.

The Company maintains standard policies of insurance that provide coverage (i) to its directors and officers against loss rising from claims made by reason of breach of duty or other wrongful act and (ii) to the Company with respect to indemnification payments that it may make to such directors and officers.

Item 16. Exhibits.

Exhibit Number	Description of the Document
1.1	At Market Issuance Sales Agreement, dated February 7, 2025 by and among SEACOR Marine Holdings Inc. and B. Riley Securities Inc.
3.1**	Third Amended and Restated Certificate of Incorporation of SEACOR Marine Holdings Inc. (incorporated herein by reference to Exhibit 3.1 to the Company’s Form 10-K filed on March 10, 2022)
3.2**	Third Amended and Restated Bylaws of SEACOR Marine Holdings Inc. (incorporated herein by reference to Exhibit 3.2 to the Company’s Form 10-K filed on March 10, 2022)
4.1**	Description of Securities registered pursuant to Section 12 of the Securities Exchange Act of 1934 (incorporated herein by reference to Exhibit 4.11 of SEACOR Marine Holdings Inc.’s Annual Report on Form 10-K filed with the Commission on March 10, 2022 (File No. 00137966))
4.2*	Form of Certificate of Designation of Preferred Stock
4.3*	Form of Common Stock Warrant Agreement and Warrant Certificate
4.4*	Form of Preferred Stock Warrant Agreement and Warrant Certificate
4.5*	Form of Unit Agreement and Unit Certificate
5.1	Opinion of Milbank LLP as to the legality of the securities being registered
23.1	Consent of Grant Thornton LLP, Independent Registered Public Accounting Firm
23.2	Consent of Milbank LLP (included in Exhibit 5.1 hereto)
24.1	Power of Attorney (incorporated by reference to the signature page hereto)
107	Filing Fee Table

* To be filed, if necessary, by amendment or as an exhibit to a report pursuant to section 13(a) or 15(d) of the Securities Exchange Act of 1934, as amended, and incorporated herein by reference

** Incorporated by reference.

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Item 17. Undertakings

(a) The undersigned registrant hereby undertakes:

(1) To file, during any period in which offers or sales are being made, a post-effective amendment to this registration statement:

(i) To include any prospectus required by Section 10(a)(3) of the Securities Act;

(ii) To reflect in the prospectus any facts or events arising after the effective date of the registration statement (or the most recent post-effective amendment thereof) which, individually or in the aggregate, represent a fundamental change in the information set forth in the registration statement. Notwithstanding the foregoing, any increase or decrease in volume of securities offered (if the total dollar value of securities offered would not exceed that which was registered) and any deviation from the low or high end of the estimated maximum offering range may be reflected in the form of prospectus filed with the SEC pursuant to Rule 424(b) if, in the aggregate, the changes in volume and price represent no more than a 20% change in the maximum aggregate offering price set forth in the “Calculation of Registration Fee” table in the effective registration statement; and

(iii) To include any material information with respect to the plan of distribution not previously disclosed in the registration statement or any material change to such information in the registration statement;

provided, however, that paragraphs (a)(1)(i), (a)(1)(ii) and (a)(1)(iii) above do not apply if the information required to be included in a post-effective amendment by those paragraphs is contained in reports filed with or furnished to the SEC by registrant pursuant to Section 13 and Section 15(d) of the Securities Exchange Act of 1934 that are incorporated by reference in the registration statement, or is contained in a form of prospectus filed pursuant to Rule 424(b) that is part of the registration statement.

(2) That, for the purpose of determining any liability under the Securities Act, each such post-effective amendment shall be deemed to be a new registration statement relating to the securities offered therein, and the offering of such securities at that time shall be deemed to be the initial bona fide offering thereof.

(3) To remove from registration by means of a post-effective amendment any of the securities being registered which remain unsold at the termination of the offering.

(4) That, for the purpose of determining liability under the Securities Act to any purchaser:

(A) Each prospectus filed by the registrant pursuant to Rule 424(b)(3) shall be deemed to be part of the registration statement as of the date the filed prospectus was deemed part of and included in the registration statement; and

(B) Each prospectus required to be filed pursuant to Rule 424(b)(2), (b)(5) or (b)(7) as part of a registration statement in reliance on Rule 430B relating to an offering made pursuant to Rule 415(a)(1)(i), (vii) or (x) for the purpose of providing the information required by Section 10(a) of the Securities Act shall be deemed to be part of and included in the registration statement as of the earlier of the date such form of prospectus is first used after effectiveness or the date of the first contract of sale of securities in the offering described in the prospectus. As provided in Rule 430B, for liability purposes of the issuer and any person that is at that date an underwriter, such date shall be deemed to be a new effective date of the registration statement relating to the securities in the registration statement to which that prospectus relates, and the offering of such securities at that time shall be deemed to be the initial bona fide offering thereof. Provided, however, that no statement made in a registration statement or prospectus that is part of the registration statement or made in a document incorporated or deemed incorporated by reference into the registration statement or prospectus that is part of the registration statement will, as to a purchaser with a time of contract of sale prior to such effective date, supersede or modify any statement that was made in the registration statement or prospectus that was part of the registration statement or made in any such document immediately prior to such effective date.

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(5) That, for the purpose of determining liability of the registrant under the Securities Act to any purchaser in the initial distribution of the securities:

The undersigned registrant undertakes that in a primary offering of securities of the undersigned registrant pursuant to this registration statement, regardless of the underwriting method used to sell the securities to the purchaser, if the securities are offered or sold to such purchaser by means of any of the following communications, the undersigned registrant will be a seller to the purchaser and will be considered to offer or sell such securities to such purchaser:

(i) Any preliminary prospectus or prospectus of the undersigned registrant relating to the offering required to be filed pursuant to Rule 424;

(ii) Any free writing prospectus relating to the offering prepared by or on behalf of the undersigned registrant or used or referred to by the undersigned registrant;

(iii) The portion of any other free writing prospectus relating to the offering containing material information about the undersigned registrant or its securities provided by or on behalf of the undersigned registrant; and

(iv) Any other communication that is an offer in the offering made by the undersigned registrant to the purchaser.

(b) The undersigned registrant hereby undertakes that, for purposes of determining any liability under the Securities Act, each filing of the registrant’s annual report pursuant to Section 13(a) or Section 15(d) of the Securities Exchange Act of 1934 (and, where applicable, each filing of an employee benefit plan’s annual report pursuant to Section 15(d) of the Securities Exchange Act of 1934) that is incorporated by reference in the registration statement shall be deemed to be a new registration statement relating to the securities offered therein, and the offering of such securities at that time shall be deemed to be the initial bona fide offering thereof.

(c) Insofar as indemnification for liabilities arising under the Securities Act may be permitted to directors, officers and controlling persons of the registrant pursuant to the foregoing provisions, or otherwise, the registrant has been advised that in the opinion of the SEC such indemnification is against public policy as expressed in the Securities Act and is, therefore, unenforceable. In the event that a claim for indemnification against such liabilities (other than the payment by the registrant of expenses incurred or paid by a director, officer or controlling person of the registrant in the successful defense of any action, suit or proceeding) is asserted by such director, officer or controlling person in connection with the securities being registered, the registrant will, unless in the opinion of its counsel the matter has been settled by controlling precedent, submit to a court of appropriate jurisdiction the question whether such indemnification by it is against public policy as expressed in the Securities Act and will be governed by the final adjudication of such issue.

(d) The undersigned registrant hereby undertakes that:

(1) For purposes of determining any liability under the Securities Act, the information omitted from the form of prospectus filed as part of this registration statement in reliance upon Rule 430A and contained in a form of prospectus filed by the registrant pursuant to Rule 424(b)(1) or (4) or 497(h) under the Securities Act shall be deemed to be part of this registration statement as of the time it was declared effective.

(2) For the purpose of determining any liability under the Securities Act, each post-effective amendment that contains a form of prospectus shall be deemed to be a new registration statement relating to the securities offered therein, and the offering of such securities at that time shall be deemed to be the initial bona fide offering thereof.

(e) The undersigned registrant hereby undertakes to file an application for the purpose of determining the eligibility of the trustee to act under subsection (a) of section 310 of the Securities Act in accordance with the rules and regulations prescribed by the SEC under section 305(b)(2) of the Securities Act.

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SIGNATURES

Pursuant to the requirements of the Securities Act of 1933, as amended, the Registrant certifies that it has reasonable grounds to believe that it meets all of the requirements for filing on Form S-3 and has duly caused this registration statement to be signed on its behalf by the undersigned, thereunto duly authorized, in the village of Larchmont, State of New York, on February 7, 2025.

SEACOR MARINE HOLDINGS INC.
By:	/s/ Jesús Llorca
	Name:	Jesús Llorca
	Title:	Executive Vice President and Chief Financial Officer

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POWER OF ATTORNEY

Each person whose signature appears below appoints John Gellert, Jesús Llorca, and Andrew H. Everett II and each of them, all of whom may act without the joinder of the others, as his or her true and lawful attorneys-in-fact and agents, with full power of substitution and re-substitution, for him or her and in his or her name, place and stead, in any and all capacities, to sign any and all amendments (including post-effective amendments) to this registration statement and any registration statement (including any amendment thereto) for this offering that is to be effective upon filing pursuant to Rule 462(b) under the Securities Act of 1933, as amended, and to file the same, with all exhibits thereto, and all other documents in connection therewith, with the Securities and Exchange Commission, granting unto said attorneys-in-fact and agents full power and authority to do and perform each and every act and thing requisite and necessary to be done, as fully to all intents and purposes as he might or would do in person, hereby ratifying and confirming all that said attorney-in-fact and agent may lawfully do or cause to be done by virtue hereof.

Pursuant to the requirements of the Securities Act of 1933, as amended, this registration statement has been signed by the following persons on behalf of the registrant and in the capacities and on the dates indicated.

Signature	Title	Date
/s/ John Gellert John Gellert	President, Chief Executive Officer and Chairman (Principal Executive Officer)	February 7, 2025
/s/ Jesús Llorca Jesús Llorca	Executive Vice President and Chief Financial Officer (Principal Financial Officer)	February 7, 2025
/s/ Gregory S. Rossmiller Gregory S. Rossmiller	Senior Vice President and Chief Accounting Officer (Principal Accounting Officer)	February 7, 2025
/s/ Andrew R. Morse Andrew R. Morse	Non-Executive Chairman of the Board	February 7, 2025
/s/ R. Christopher Regan R. Christopher Regan	Director	February 7, 2025
/s/ Julie Persily Julie Persily	Director	February 7, 2025
/s/ Alfredo Miguel Bejos Alfredo Miguel Bejos	Director	February 7, 2025
/s/ Lisa P. Young Lisa P. Young	Director	February 7, 2025

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