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                                                                     EXHIBIT 8.1


                   [Letterhead of Weil, Gotshal & Manges LLP]
                                  June 26, 2001


Diamond Offshore Drilling, Inc.
15415 Katy Freeway
Houston, Texas 77094

Ladies and Gentlemen:

         We have acted as counsel to Diamond Offshore Drilling, Inc. (the
"Company") in connection with the preparation and filing of a Registration
Statement on Form S-3 (the "Registration Statement") pursuant to the Securities
Act of 1933, as amended (the "Securities Act"), relating to the registration for
resale under the Securities Act of $460,000,000 aggregate principal amount of
the Company's 1-1/2% Convertible Senior Debentures Due 2031 (the "Debentures"),
which may be converted in certain cases into shares of the Company's common
stock, par value $.01 per share.

         In connection with our opinion we have reviewed the Registration
Statement, including the exhibits thereto, and such other documents, records and
instruments as we have deemed necessary or appropriate for purposes of this
opinion. In such examination, we have assumed the genuineness of all signatures,
the legal capacity of all natural persons, the authenticity of all documents
submitted to us as originals, the conformity to original documents of all
documents submitted to us as certified, conformed or photostatic copies and the
authenticity of the originals of such latter documents.

         We hereby confirm that, although the discussion set forth in the
Registration Statement under the heading "CERTAIN UNITED STATES FEDERAL INCOME
TAX CONSIDERATIONS" does not purport to discuss all possible United States
federal income tax considerations of the purchase, ownership and disposition of
the Debentures, in our opinion such discussion constitutes, in all material
respects, a fair and accurate summary of the United States federal income tax
considerations of the purchase, ownership and disposition of the Debentures,
based upon current United States federal income tax law. There can be no
assurances, however, that any of the opinions expressed herein will be accepted
by the Internal Revenue Service or, if challenged, by a court of law.

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Diamond Offshore Drilling, Inc.
June 26, 2001
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         This opinion is delivered in accordance with the requirements of Item
601(b)(8) of Regulation S-K under the Securities Act. In rendering our opinion,
we have considered the applicable provisions of the Internal Revenue Code of
1986, as amended, Treasury Department regulations promulgated thereunder,
pertinent judicial authorities, interpretive rulings of the Internal Revenue
Service and such other authorities as we have considered relevant. It should be
noted that statutes, regulations, judicial decisions and administrative
interpretations are subject to change at any time (possibly with retroactive
effect). A change in the authorities or the accuracy or completeness of any of
the information, documents, certificates, records, statements, representations,
covenants or assumptions on which our opinion is based could affect our
conclusions. This opinion is expressed as of the date hereof, and we are under
no obligation to supplement or revise our opinion to reflect any changes
(including changes that have retroactive effect) in applicable law or any
information, document, certificate, record, statement, representation, covenant
or assumption relied upon herein that becomes incorrect or untrue.

         This opinion is delivered to you solely for use in connection with the
Registration Statement and is not to be used, circulated, quoted or otherwise
referred to for any other purpose, or relied upon by any other person, without
our express written permission. In accordance with the requirements of Item
601(b)(23) of Regulation S-K under the Securities Act, we hereby consent to the
filing of this opinion as an exhibit to the Registration Statement, and to the
reference to our firm in the Registration Statement. In giving such consent, we
do not hereby admit that we are in the category of persons whose consent is
required under Section 7 of the Securities Act or the rules or regulations of
the Securities and Exchange Commission thereunder.


                                             Very truly yours,



                                             /s/ Weil, Gotshal & Manges LLP