EXHIBIT 5.4

                                 [LETTERHEAD OF]

                      BARROS Y ERRAZURIZ ABOGADOS LIMITADA

                                                               January____, 2005

Ultrapetrol (Bahamas) Limited
c/o H&J Corporate Services Ltd.
Shirlaw House
87 Shirley Street
P.O. Box SS-19084
Nassau, Bahamas

              Re:   9% First Preferred Ship Mortgage Notes due 2014

Ladies and Gentlemen:

      We have acted as special Chilean counsel to Ultrapetrol (Bahamas) Limited,
a Bahamas company (the "Company") and to Corporacion de Navegacion Mundial S.A.,
a (corporation) organized and existing under the laws of the Republic of Chile,
and one of the Company's subsidiaries (the "Guarantor" and, together with the
Company, the "Ultrapetrol Group") in connection with the Company's Registration
Statement on Form F-4 (the "Registration Statement") as filed with the United
States Securities and Exchange Commission (the "Commission"), with respect to
the Company's offer to exchange (the "Exchange Offer") up to $180,000,000 of the
Company's 9% First Preferred Ship Mortgage Notes due 2014 (the "Exchange Notes")
for an identical principal amount at maturity of its outstanding 9% First
Preferred Ship Mortgage Notes due 2014 (the "Outstanding Notes"). The Exchange
Notes are to be issued pursuant to the Indenture dated as of November 24, 2004
between the Company, the Guarantor and Manufacturers Traders and Trust Company,
as Trustee (the "Trustee") (the "Indenture") and, when issued, will be
guaranteed by the Guarantor (the "Guarantee") pursuant to the Indenture.
Capitalized terms not defined herein have the meanings ascribed to them in the
Registration Statement.

      We have examined originals or copies, certified or otherwise identified to
our satisfaction, of: (i) the Registration Statement; (ii) the prospectus of the
Company (the "Prospectus") included in the Registration Statement; (iii) the
Indenture; (iv) the form of the Outstanding Notes; (v) the form of the Exchange
Notes and (vi) such corporate documents and records of the Company and the
Guarantor and such other instruments, certificates and documents as we have
deemed necessary or appropriate as a basis for the opinions hereinafter



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January_____, 2005]
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expressed (collectively the "Documents"). In such examinations, we have assumed
and not verified:

      (a)   the authenticity of all documents submitted to us as originals;

      (b)   the conformity to original documents of all documents submitted to
            us as copies or drafts of documents to be executed;

      (c)   the genuineness of all signatures and the legal competence or
            capacity of persons or entities (whoever are or will become
            signatories thereto) to complete the execution of documents;

      (d)   the due compliance of the Documents with all matters of, and the
            validity and enforceability thereof under, all such laws as govern
            or relate to them (other than the laws of Chile as to which we are
            opining);

      (e)   that any required consents, licenses, permits, approvals, exemptions
            or authorizations of or by any governmental authority or regulatory
            body of any jurisdiction other than Chile in connection with the
            transactions contemplated by the Documents have been obtained.

      As to various questions of fact that are material to the opinion
hereinafter expressed, we have relied upon statements or certificates of public
officials, directors or officers of the Company and the Guarantor and others.

      We have further assumed for the purposes of this opinion that each of the
Indenture and all documents contemplated by the Indenture to be executed in
connection with the issuance of the Exchange Notes and Guarantee have been duly
authorized and validly executed and delivered by each of the parties thereto
other than the Company and the Guarantor.

      Based upon and subject to the foregoing, and having regard to such other
legal considerations which we deem relevant, we are of the opinion that the
Guarantee to which the Guarantor is a party have been duly authorized, executed
and delivered by it.

      We hereby confirm that the discussion under the headings "Enforceability
of Civil Liabilities" and "Summary of the Terms of the Exchange Notes:
Additional Amounts" contained in the Company's Registration Statement on Form
F-4, insofar as such discussion represents legal conclusions or statements of
Chile law, subject to the limitations and conditions set forth therein,
constitutes the opinion of Barros & Errazuriz Abogados Ltda. and fairly presents
the information disclosed therein in all material respects.

      This opinion is limited to the laws of Chile. This opinion is rendered as
of the date hereof, and we have no responsibility to update this opinion for
events or circumstances



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January_____, 2005]
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occurring after the date hereof, nor do we have any responsibility to advise you
of any change in the laws after the date hereof.

      We hereby consent to the filing of this opinion as an exhibit to the
Company's Registration Statement on Form F-4 to be filed with the United States
Securities and Exchange Commission with respect to the Exchange Notes, without
admitting we are "experts" within the meaning of the Securities Act of 1933, as
amended, or the rules and regulations of the Commission thereunder with respect
to any part of the Registration Statement.

                                                       Very truly yours,

                                                       BARROS Y ERRAZURIZ
                                                       ABOGADOS LIMITADA