SUBORDINATED PROMISSORY NOTE

$1,074,480.09                Lafayette, Louisiana                   May 13, 2005

      For value received, OMNI ENERGY SERVICES CORP., a Louisiana corporation
("Borrower"), promises to pay to PORTSIDE GROWTH AND OPPORTUNITY FUND, a Cayman
Islands corporation ("Lender"), c/o Ramius Capital Group, LLC, at 666 Third
Avenue, 26th Floor, New York, New York 10017, or at such other address as Lender
shall from time to time specify in writing, the principal sum of ONE MILLION
SEVENTY-FOUR THOUSAND FOUR HUNDRED EIGHTY AND 09/100 DOLLARS ($1,074,480.09), in
legal and lawful money of the United States of America, with interest on the
outstanding principal from the date advanced until paid at the rate set out
below. Interest shall be computed on a per annum basis of a year of 365 days or
366 days in a leap year, as the case may be, and for the actual number of days
elapsed.

      1. PAYMENT TERMS. Principal and interest shall be due and payable in
quarterly payments of $101,628.66 each, payable on the thirteenth day of August,
November, February, and May of each calendar year beginning August 13, 2005, and
continuing regularly and quarterly thereafter until May 13, 2008, when the
entire amount hereof, principal and interest then remaining unpaid, shall be
then due and payable; interest being calculated on the unpaid principal each day
principal is outstanding and all payments made credited to any collection costs
and late charges, to the discharge of the interest accrued and to the reduction
of the principal, in such order as Lender shall determine.

      2. INTEREST RATE. The unpaid principal balance of this Note shall bear
interest prior to maturity (however such maturity is brought about) at a fixed
rate of eight percent (8%) per annum.

      3. DEFAULT RATE. Unpaid principal and interest shall bear interest from
date due until paid at (a) the highest rate permitted by applicable law, or (b)
if no such maximum rate is established by applicable law, at the rate stated
above plus five percent (5%) per annum.

      4. PREPAYMENT.

            (a) Borrower reserves the right to prepay, prior to maturity, all or
      any part of the principal of this Note without penalty. Any prepayments
      shall be applied first to accrued interest and then to principal. Borrower
      will provide written notice to the Lender of any such prepayment of all or
      any part of the principal at the time thereof. All payments and
      prepayments of principal or



      interest on this Note shall be made in lawful money of the United States
      of America in immediately available funds, at the address of Lender
      indicated above, or such other place as the Lender shall designate in
      writing to Borrower. All partial prepayments of principal shall be applied
      to the last installments payable in their inverse order of maturity.

            (b) In the event that the aggregate amount of Borrower's
      Indebtedness (as that term is defined in the Settlement Agreement and
      Mutual Release of even date herewith among Lender, Ramius Capital Group,
      LLC, and Borrower exceeds $52,346,462 (the "Indebtedness Cap"), then
      within three (3) business days after receipt by Borrower of written notice
      from Lender of such occurrence, the Borrower shall pay, in full, all of
      the outstanding principal and accrued interest remaining on the Note.
      Borrower agrees to give prompt written notice to Lender when Borrower's
      Indebtedness exceeds the Indebtedness Cap.

      5. DEFAULT. It is expressly provided that:

            (a) upon default in the punctual payment of this Note or any part
      hereof, principal or interest, as the same shall become due and payable
      and such default continues for a period of five (5) days,

            (b) in the event of a default under the terms of any Senior Debt (as
      defined in Paragraph 8 below), which default is not cured within
      applicable time periods,

            (c) the Borrower shall default in the observance or performance in
      any material respect of any of the representations, warranties, covenants
      or agreements contained in the Settlement Agreement and Mutual Release of
      even date herewith among Borrower, Lender and Ramius Capital Group, LLC,
      the 2005 Registration Rights Agreement of even date herewith among
      Borrower and Lender or the Escrow Agreement of even date herewith by and
      among Borrower, Lender and the escrow agent; or James Eckert or his
      successor ("Eckert") shall default in the observance or performance in any
      material respect of any covenants or agreements contained in the Voting
      Agreement of even date herewith between Lender and Eckert, or

            (d) Borrower makes an assignment for the benefit of creditors, or
      becomes a party to a voluntary or involuntary proceeding under state law
      or under any chapter of the United States Bankruptcy Code and, in the case
      of an involuntary proceeding, such proceeding remains undismissed for a
      period of 60 days,

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then and in any such event, the Lender may, at its option, without further
notice or demand, (i) declare the outstanding principal balance of and accrued
but unpaid interest on this Note at once due and payable, (ii) pursue any and
all other rights, remedies and recourses available to the Lender hereof, at law
or in equity, or (iii) pursue any combination of the foregoing; and in the event
default is made in the prompt payment of this Note when due or declared due, and
the same is placed in the hands of an attorney for collection, or suit is
brought on same, or the same is collected through probate, bankruptcy or other
judicial proceedings, then the Borrower agrees and promises to pay all costs of
collection, including reasonable attorney's fees. In the alternative, in the
event that Borrower has defaulted in any quarterly payment under this Note, and
such default has not been cured within five (5) days, Lender may elect, by
notice to the Borrower and the Escrow Agent (as defined below) to receive in the
quarterly payment in shares of stock, based upon the formula set forth in
Paragraph 8 below.

      6. WAIVER. Borrower, as well as all successors and legal representatives
of said Borrower, shall be directly and primarily liable for the payment of all
indebtedness hereunder. Except as specifically provided herein, Borrower
expressly waives presentment and demand for payment, notice of default, notice
of intent to accelerate maturity, notice of acceleration of maturity, protest,
notice of protest, notice of dishonor, and all other notices and demands for
which waiver is not prohibited by law, and diligence in the collection hereof;
and agrees to all renewals, extensions, indulgences, partial payments, with or
without notice, before or after maturity. No delay or omission of Lender in
exercising any right hereunder shall be a waiver of such right or any other
right under this Note.

      7. NO USURY INTENDED; USURY SAVINGS CLAUSE. In no event shall interest
contracted for, charged or received hereunder, plus any other charges in
connection herewith which constitute interest, exceed the maximum interest
permitted by applicable law. The amounts of such interest or other charges
previously paid to the Lender in excess of the amounts permitted by applicable
law shall be applied by the Lender to reduce the principal of the indebtedness
evidenced by the Note, or, at the option of the Lender, be refunded. To the
extent permitted by applicable law, determination of the legal maximum amount of
interest shall at all times be made by amortizing, prorating, allocating and
spreading in equal parts during the period of the full stated term of the loan
and indebtedness, all interest at any time contracted for, charged or received
from the Borrower hereof in connection with the loan and indebtedness evidenced
hereby, so that the actual rate of interest on account of such indebtedness is
uniform throughout the term hereof.

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      8. SUBORDINATION.

            (a) This Note shall be subordinate and junior in right of payment to
      all Senior Debt. As used in this Paragraph 8, "Senior Debt" shall mean and
      include all indebtedness, obligations and liabilities of the Borrower owed
      to (i) General Electric Capital Corporation ("GECC") as described, and
      only to the extent provided, in the GECC Subordination Agreement; and (ii)
      Webster Business Credit Corporation ("Webster") as described, and only to
      the extent provided, in that certain Subordination and Intercreditor
      Agreement dated as of even date herewith, among Webster, Lender, and
      certain other creditors of Borrower.

            (b) In the event that the terms of the subordination agreements
      described in subparagraph (a) prohibit the cash payment to Lender of any
      regularly scheduled quarterly payment of principal and interest due
      hereunder as a result of a default by Borrower on the Senior Debt (other
      than a default arising from Borrower's failure to pay any amount due to
      GECC or Webster under the terms of such Senior Debt), Lender shall be
      entitled to elect to receive shares ("Debt Service Shares") of Borrower's
      Common Stock, $.01 par value per share ("Common Stock"), in lieu of such
      cash payment. In the event that Lender elects to receive shares of Common
      Stock pursuant to this subparagraph (b), the number of shares of Common
      Stock to be issued shall be equal to the aggregate amount of the principal
      and interest to be paid to Lender divided by the applicable VWAP Formula
      (as defined below). In the event that Lender elects to receive Debt
      Service Shares, Lender shall notify Borrower of such decision, in writing,
      on or after the due date of such payment.

            (c) For purposes of this Paragraph 8, the following terms shall have
      the meaning set forth below:

                  (i) "VWAP Formula" shall mean ("A") in the event that the
            issuance of stock, would otherwise violate Rule 4350(i) of the
            National Association of Securities Dealers, the average (the "VWAP
            Average") of the VWAP of a share of Common Stock for the five (5)
            Trading Days immediately preceding the date such payment was due to
            Lender or (B) in all other cases, ninety percent (90%) of the VWAP
            Average.

                  (ii) "Trading Day" means any day on which the Common Stock is
            purchased or sold on the principal securities exchange or market on
            which the Common Stock is then listed or traded.

                  (iii) "VWAP" on a Trading Day means the volume weighted
            average price of the Common Stock for such Trading Day as reported
            by

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            Bloomberg Financial Markets or if Bloomberg Financial Markets has
            not been reporting such prices by a comparable reporting service of
            national reputation selected by Lender and reasonably satisfactory
            to the Borrower.

            (d) In the event that the VWAP Formula used is the VWAP Average,
      then 10% of the amount of principal and interest to be paid to the Lender
      in the relevant paragraph shall be added to the principal balance of this
      Note.

      9. ESCROW AGREEMENTS; PAYMENT IN SHARES OF COMMON STOCK. Pursuant to the
Escrow Agreement, Lender shall make notices to the escrow agent named therein to
release certain shares of Common Stock escrowed thereunder for purposes of this
Note, for payments in stock due and payable pursuant to Paragraphs 5 and 8
above. Provided, however, that in the event that Lender shall not have received
the full amount of the applicable Common Stock payment as a result of Borrower's
failure to perform its obligations under the Escrow Agreement, Borrower shall
remain fully liable for such deficiency.

      10. NOTICES. All notices, requests, demands and other communications
required or permitted hereunder shall be in writing, and shall be deemed to be
given or delivered when actually received by the party to whom directed, or, if
earlier and regardless of whether actually received, upon deposit in a regularly
maintained receptacle for the United States mail, registered or certified,
postage fully prepaid, addressed to the party to whom directed at its address
set forth below or at such other address as such party may have previously
specified by notice actually received by the other party:

      If to Borrower:      OMNI Energy Services Corp.
                           4500 NE Evangeline Thruway
                           Carencro, LA  70520
                           Attention:  G. Darcy Klug

      If to Lender:        Portside Growth and Opportunity Fund
                           c/o Ramius Capital Group, LLC
                           666 Third Avenue, 26th Floor
                           New York, New York 10017
                           Attention:  Jeffrey C. Smith, Michael R. Neidell

      11. GOVERNING LAW, VENUE. This Note is being delivered, and is intended to
be performed in the State of New York. Except to the extent that the laws of the
United States may apply to the terms hereof, the substantive laws of the State
of New York shall govern the validity, construction, enforcement and
interpretation of this Note.

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      12. CAPTIONS. The captions in this Note are inserted for convenience only
and are not to be used to limit the terms herein.

                                         BORROWER:
                                         OMNI ENERGY SERVICES CORP.

                                         By: /s/ G. Darcy Klug
                                            -----------------------------------
                                             Name:  G. Darcy Klug
                                             Title:  Executive Vice President

THIS NOTE AND THE INDEBTEDNESS EVIDENCED HEREBY ARE SUBORDINATED IN THE MANNER
AND TO THE EXTENT SET FORTH IN THOSE CERTAIN SUBORDINATION AND INTERCREDITOR
AGREEMENTS (THE "SUBORDINATION AGREEMENTS") DATED AS OF MAY 13, 2005, AMONG THE
"SUBORDINATED CREDITORS" DEFINED AND DESCRIBED THEREIN ("SUBORDINATED
CREDITORS") AND GENERAL ELECTRIC CAPITAL CORPORATION, NOT INDIVIDUALLY, BUT AS
AGENT FOR ITSELF AND CERTAIN OTHER FINANCIAL INSTITUTIONS IDENTIFIED THEREIN,
AND WEBSTER BUSINESS CREDIT CORPORATION, RESPECTIVELY, AS SUCH SUBORDINATION
AGREEMENTS MAY BE AMENDED, SUPPLEMENTED, MODIFIED, REPLACED OR REFINANCED.

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