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                                                                    EXHIBIT 10.1


                           AMENDMENT AND WAIVER NO. 1

         THIS AMENDMENT AND WAIVER NO. 1, dated as of July 31, 1997 (this
"Amendment"), to the Second Amended and Restated Credit Agreement, dated as of
December 13, 1996 (as amended, supplemented or otherwise modified prior to the
date hereof, the "Credit Agreement"), among LEVIATHAN GAS PIPELINE PARTNERS,
L.P., a Delaware limited partnership (the "Borrower"), the banks and other
financial institutions (the "Lenders") parties hereto, THE CHASE MANHATTAN
BANK, a New York banking corporation, as administrative agent (in such capacity
the "Administrative Agent") for the Lenders and ING (U.S.) CAPITAL CORPORATION,
a Delaware corporation, as co-arranger for the Lenders (the "Co-Arranger").

                              W I T N E S S E T H:

         WHEREAS, the Borrower has requested the Administrative Agent, the
Co-Arranger and the Lenders to amend the Net Worth covenant and the Ratio of
Debt to Capitalization on the Credit Agreement and to agree to waive certain
prior defaults as set forth in this amendment;

         WHEREAS, the Administrative Agent, the Co-Arranger and the Lenders are
willing to agree to such amendment, but only on the terms and subject to the
conditions set forth in this Amendment;

         NOW, THEREFORE, in consideration of the premises and for other good
and valuable consideration, the sufficiency of which is hereby acknowledged,
the Borrower, the Administrative Agent, the Co-Arranger and the undersigned
Lenders hereby agree as follows:

         1.       Definitions. Unless otherwise defined herein, terms defined
                  in the Credit Agreement are used herein as therein defined.

         2.       Amendments. Subject to the satisfaction of the provisions
                  specified in Sections 4 and 5 below, the Credit Agreement
                  shall be amended on the Effective Date (as defined below) as
                  follows:

                  (i)      Subsection 8.1(a). shall be deleted in its entirety,
         and replaced with the following:

                           (a) Tangible Net Worth. Permit Consolidated Tangible
                           Net Worth at any time (the "date of determination")
                           to be less than an amount equal to the sum of (i)
                           $125,000,000 plus (ii) an amount equal to 75% of Net
                           Equity Proceeds during the period from March 1, 1996
                           to the date of determination.

                  (ii)     Subsection 8.1(b) shall be deleted in its entirety
         and replaced with the following:


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                           (b) Ratio of Debt to Capitalization. Permit the
                           ratio of (i) Consolidated Total Indebtedness of the
                           Borrower at any time to (ii) Consolidated Total
                           Capitalization at such time, expressed as a
                           percentage, to exceed 70%.

         3. Waivers. Each of the Administrative Agent, the Co-Arranger and the
Lenders hereby waives any Default or Event of Default under subsection 8.1(a)
or 8.1(b) of the Credit Agreement in effect prior to the execution of this
Amendment to the extent such Default or Event of Default would not have been an
Event of Default or Default if the Amendment had been effective as of the date
of the Default or Event of Default.

         4. Effectiveness. This Amendment shall become effective on the date
(the "Effective Date") the following conditions precedent are first satisfied:

                  (a) The Administrative Agent shall have received evidence
satisfactory to the Administrative Agent that this Amendment has been executed
and delivered by the Borrower, the Co-Arranger, the Required Lenders and each
of the Subsidiary Guarantors.

                  (b) The Administrative Agent shall have received, a
certificate of the Borrower, dated the Effective Date, as to the incumbency and
signature of the officers of the Borrower executing this Amendment,
satisfactory in form and substance to the Administrative Agent, executed by the
Chief Executive Officer, Chief Operating Officer, Chief Financial Officer,
president, Treasurer or any Vice President and the Secretary or any Assistant
Secretary of the Borrower.

                  (c) This Amendment, shall not contravene, violate or conflict
with, nor involve any Lender in any violation of, any Contractual Obligation or
Requirement of Law.

                  (d) The Borrower shall pay to each of the Lenders signing
this Amendment on or before July 31, 1997 a work fee in the amount of $5,000 
per Lender.

         5. Representations and Warranties. To induce the Administrative Agent,
the Co-Arranger and the Required Lenders to enter into this Amendment, the
Borrower hereby represents and warrants to the Administrative Agent and the
Required Lenders that, after giving effect to the amendments and waivers
provided for herein, (i) this Amendment constitutes the legal, valid and
binding obligations of each of the Loan Parties hereto, (ii) the
representations and warranties contained in the Credit Agreement and the other
Loan Documents will be true and correct in all material respects as if made on
and as of the date hereof (unless such representations or warranties are stated
to refer to a specific earlier date, in which case such representations and
warranties shall be true and correct in all material respects as of such
earlier date) and (iii) no Default or Event of Default will have occurred and
be continuing.

         6. No Other Waivers or Amendments. Except as expressly waived or
amended hereby, the Credit Agreement, the Notes and the other Loan Documents
shall remain in full force 

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and effect in accordance with their respective terms, without any waiver,
amendment or modification of any provision thereof.

         7. Counterparts. This Amendment may be executed by one or more of the
parties hereto on any number of separate counterparts and all of said
counterparts taken together shall be deemed to constitute one and the same
instrument.

         8. Applicable Law. THIS AMENDMENT SHALL BE GOVERNED BY, AND CONSTRUED
AND INTERPRETED IN ACCORDANCE WITH, THE LAW OF THE STATE OF NEW YORK.

         9. Payment of Expenses. The Borrower agrees to pay and reimburse the
Agent for all of its out-of-pocket costs and reasonable expenses incurred in
connection with this Amendment, including, without limitation, the reasonable
fees and disbursements of legal counsel to the Agent.



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         IN WITNESS WHEREOF, the parties hereto have caused this Amendment to
be duly executed and delivered by its proper and duly authorized officer as of
the day and year first above written.

                                  LEVIATHAN GAS PIPELINE PARTNERS, L.P.


                                  By:
                                      ------------------------------------------
                                           Name:
                                           Title:

                                  THE CHASE MANHATTAN BANK, as Administrative 
                                  Agent and as a Lender


                                  By:
                                      ------------------------------------------
                                           Name:
                                           Title:

                                  ING (U.S.) CAPITAL CORPORATION, as Co-Arranger
                                  and as a Lender


                                  By:
                                      ------------------------------------------
                                           Name:
                                           Title:

                                  DEN NORSKE BANK AS


                                  By:
                                      ------------------------------------------
                                           Name:
                                           Title:


                                  By:
                                      ------------------------------------------
                                           Name:
                                           Title:



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<PAGE>   5



                                  WELLS FARGO BANK TEXAS, N.A.


                                  By:
                                      ------------------------------------------
                                           Name:
                                           Title:

                                  MEESPIERSON N.V.


                                  By:
                                      ------------------------------------------
                                           Name:
                                           Title:


                                  BANK OF SCOTLAND

                                  By:
                                      ------------------------------------------
                                           Name:
                                           Title:


                                  BANQUE PARIBAS

                                  By:
                                      ------------------------------------------
                                           Name:
                                           Title:

                                  By:
                                      ------------------------------------------
                                           Name:
                                           Title:


                                  CREDIT LYONNAIS CAYMAN ISLAND BRANCH

                                  By:
                                      ------------------------------------------
                                           Name:
                                           Title:


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                                  FIRST UNION NATIONAL BANK OF NORTH CAROLINA

                                  By:
                                      ------------------------------------------
                                           Name:
                                           Title:

                                  ARAB BANKING CORPORARTION (B.S.C.)

                                  By:
                                      ------------------------------------------
                                           Name:
                                           Title:

                                  CREDIT AGRICOLE


                                  By:
                                      ------------------------------------------
                                           Name:
                                           Title:


                                  PNC BANK, NATIONAL ASSOCIATION

                                  By:
                                      ------------------------------------------
                                           Name:
                                           Title:


                                  THE BANK OF NOVA SCOTIA

                                  By:
                                      ------------------------------------------
                                           Name:
                                           Title:


                                  HIBERNIA NATIONAL BANK

                                  By:
                                      ------------------------------------------
                                           Name:
                                           Title:



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         The undersigned guarantors hereby consent and agree to the foregoing
Amendment:

DELOS OFFSHORE COMPANY, L.L.C.

By:
    ------------------------------------
         Title:

EWING BANK GATHERING COMPANY, L.L.C.

By:
    ------------------------------------
         Title:

FLEXTREND DEVELOPMENT COMPANY, L.L.C.

By:
    ------------------------------------
         Title:

GREEN CANYON PIPE LINE COMPANY, L.L.C.

By:
    ------------------------------------
         Title:

LEVIATHAN OIL TRANSPORT SYSTEMS, L.L.C.

By:
    ------------------------------------
         Title:

MANTA RAY GATHERING COMPANY, L.L.C.

By:
    ------------------------------------
         Title:

POSEIDON PIPELINE COMPANY, L.L.C.

By:
    ------------------------------------
         Title:




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STINGRAY HOLDING, L.L.C.


By:
    -------------------------------------
         Name:
         Title:

TARPON TRANSMISSION COMPANY

By:
    -------------------------------------
         Title:

TRANSCO HYDROCARBONS COMPANY, L.L.C.

By:
    -------------------------------------
         Title:

TEXAM OFFSHORE GAS TRANSMISSION, L.L.C

By:
    -------------------------------------
         Title:

TRANSCO OFFSHORE PIPELINE COMPANY, L.L.C.

By:
    -------------------------------------
         Title:

VK DEEPWATER GATHERING COMPANY, L.L.C.

By:
    -------------------------------------
         Title:

VK-MAIN PASS GATHERING COMPANY, L.L.C.

By:
    -------------------------------------
         Title:

SAILFISH PIPELINE COMPANY, L.L.C.

By:
    -------------------------------------
         Title:



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