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                                                                  EXHIBIT 4.7.1


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                          EL PASO ENERGY PARTNERS, L.P.
          EL PASO ENERGY PARTNERS FINANCE CORPORATION, AS THE ISSUERS,

                                       AND

             THE SUBSIDIARIES PARTY HERETO, AS SUBSIDIARY GUARANTORS

                                       AND

              CHASE BANK OF TEXAS, NATIONAL ASSOCIATION, AS TRUSTEE

                              --------------------

                          THIRD SUPPLEMENTAL INDENTURE

                           DATED AS OF MARCH 21, 2000

                                       TO

                                    INDENTURE

                            DATED AS OF MAY 27, 1999
                              --------------------


                                  $175,000,000

              10 3/8% SENIOR SUBORDINATED NOTES DUE 2009, SERIES A
              10 3/8% SENIOR SUBORDINATED NOTES DUE 2009, SERIES B




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                          THIRD SUPPLEMENTAL INDENTURE

         THIS THIRD SUPPLEMENTAL INDENTURE (this "Supplemental Indenture"),
dated as of March 21, 2000, is by and among El Paso Energy Partners, L.P., a
Delaware limited partnership (formerly Leviathan Gas Pipeline Partners, L.P.),
El Paso Energy Partners Finance Corporation, a Delaware corporation (formerly
Leviathan Finance Corporation), the guarantor parties hereto, and Chase Bank of
Texas, National Association, a national banking association, as trustee.

                              W I T N E S S E T H:

         WHEREAS, the Issuers (herein defined), the Subsidiary Guarantors
(herein defined) and the Trustee (herein defined) entered into an Indenture,
dated as of May 27, 1999 (the "Indenture"), relating to $175,000,000 of the
Company's 10 3/8% Senior Subordinated Notes due 2009;

         WHEREAS, the Restricted Subsidiary (herein defined) Green Canyon Pipe
Line Company, L.L.C., a Delaware limited liability company, has been converted
into Green Canyon Pipe Line Company, L.P., a Delaware limited partnership (the
"New Guarantor"), which will become a Subsidiary Guarantor under the Indenture
pursuant to the terms of this Supplemental Indenture.

         WHEREAS, this Supplemental Indenture is executed and delivered pursuant
to Sections 4.14 and 11.01 of the Indenture;

         WHEREAS, the Issuers, the Subsidiary Guarantors (which term includes
the New Guarantor) and the Trustee desire to enter into this Supplemental
Indenture to provide for the New Guarantor's guarantee of the payment of
securities on the same terms and conditions as the Guarantees by the other
Subsidiary Guarantors;

         WHEREAS, all conditions precedent provided for in the Indenture
relating to this Supplemental Indenture have been complied with; and

         NOW, THEREFORE, in consideration of the premises herein contained, and
for other good and valuable considerations, the receipt and sufficiency of which
are hereby acknowledged, the Issuers, the Subsidiary Guarantors and the Trustee
mutually covenant and agree for the equal and proportionate benefit of all
Holders (herein defined) of the Notes (herein defined) as follows:

               SECTION 1. INCORPORATION OF INDENTURE; DEFINITIONS

         1.1 INCORPORATION OF INDENTURE. This Supplemental Indenture constitutes
a supplement to the Indenture, and the Indenture and this Supplemental Indenture
shall be read together and shall have effect so far as practicable as though all
of the provisions thereof and hereof are contained in one instrument.

         1.2 DEFINITIONS. All capitalized terms used herein and not otherwise
defined herein shall have the respective meanings assigned to such terms in the
Indenture.


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                       SECTION 2. SUPPLEMENTAL PROVISIONS

         2.1 UNCONDITIONAL GUARANTEE. Subject to the provisions of Article 11 of
the Indenture, the New Guarantor shall be a Subsidiary Guarantor under the terms
of the Indenture and hereby unconditionally guarantees to each Holder of a Note
authenticated and delivered by the Trustee and to the Trustee and its successors
and assigns, irrespective of the validity and enforceability of the Indenture,
the Notes or the Obligations of the Issuers under the Indenture or the Notes,
that:

         (a) the principal of, premium, interest and Liquidated Damages, if any,
             on the Notes shall be promptly paid in full when due, whether at
             the maturity or interest payment or mandatory redemption date, by
             acceleration, redemption or otherwise, and interest on the overdue
             principal of, premium, interest and Liquidated Damages, if any, on
             the Notes, if any, if lawful, and all other Obligations of the
             Issuers to the Holders or the Trustee under the Indenture and the
             Notes shall be promptly paid in full or performed, all in
             accordance with the terms of the Indenture and the Notes; and

         (b) in case of any extension of time of payment or renewal of any Notes
             or any of such other obligations, that same shall be promptly paid
             in full when due or performed in accordance with the terms of the
             extension or renewal, whether at Stated Maturity, by acceleration
             or otherwise. Failing payment when due of any amount so guaranteed
             or any performance so guaranteed for whatever reason, the
             Subsidiary Guarantors shall be jointly and severally obligated to
             pay the same immediately.

The New Guarantor hereby agrees that its obligations hereunder and under the
Indenture shall be unconditional, irrespective of the validity, regularity or
enforceability of the Notes or the Indenture, the absence of any action to
enforce the same, any waiver or consent by any Holder of the Notes with respect
to any provisions of the Indenture and the Notes, the recovery of any judgment
against the Issuers, any action to enforce the same or any other circumstance
which might otherwise constitute a legal or equitable discharge or defense of a
Subsidiary Guarantor. The New Guarantor hereby waives diligence, presentment,
demand of payment, filing of claims with a court in the event of insolvency or
bankruptcy of the Issuers, any right to require a proceeding first against the
Issuers, protest, notice and all demands whatsoever and covenant that the
Guarantees shall not be discharged except by complete performance of the
obligations contained in the Notes and the Indenture.

         If any Holder or the Trustee is required by any court or otherwise to
return to the Issuers or Subsidiary Guarantors, or any custodian, trustee,
liquidator or other similar official acting in relation to either the Issuers or
Subsidiary Guarantors, any amount paid by either to the Trustee or such Holder,
these Guarantees, to the extent theretofore discharged, shall be reinstated in
full force and effect. The New Guarantor agrees that it shall not be entitled to
any right of subrogation in relation to the Holders in respect of any
obligations guaranteed under the Indenture until payment in full of all
obligations guaranteed under the Indenture.

         The New Guarantor further agrees that, as between the Subsidiary
Guarantors, on the one hand, and the Holders and the Trustee, on the other hand,
(x) the maturity of the Obligations guaranteed under the Indenture may be
accelerated as provided in Article 6 of the Indenture for the purposes of these
Guarantees, notwithstanding any stay, injunction or other prohibition preventing


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such acceleration in respect of the obligations guaranteed under the Indenture,
and (y) in the event of any declaration of acceleration of such Obligations as
provided in Article 6 of the Indenture, such Obligations (whether or not due and
payable) shall forthwith become due and payable by the Subsidiary Guarantors for
the purpose of these Guarantees. The New Guarantor agrees that the Subsidiary
Guarantors shall have the right to seek contribution from any non-paying
Subsidiary Guarantor so long as the exercise of such right does not impair the
rights of the Holders under these Guarantees.

         2.2 OTHER GUARANTEE TERMS. The New Guarantor hereby confirms, adopts
and acknowledges each of the provisions of the Indenture relating to the
Subsidiary Guarantors and the Guarantees, including, but not limited to Articles
4 and 11.

                            SECTION 3. MISCELLANEOUS

         3.1 COUNTERPARTS. This Supplemental Indenture may be signed in
counterparts and by the different parties hereto in separate counterparts, each
of which shall constitute an original and all of which together shall constitute
one and the same instrument.

         3.2 SEVERABILITY. In case any provision in this Supplemental Indenture
shall be invalid, illegal or unenforceable, the validity, legality and
enforceability of the remaining provisions shall not in any way be affected or
impaired thereby.

         3.3 HEADINGS. The headings of the Sections of this Supplemental
Indenture have been inserted for convenience of reference only, are not to be
considered a part hereof and shall not modify or restrict any of the terms or
provisions hereof.

         3.4 SUCCESSORS. All agreements of the Issuers and the Subsidiary
Guarantors in this Supplemental Indenture shall bind their respective
successors. All agreements of the Trustee in this Supplemental Indenture shall
bind its successors.

         3.5 GOVERNING LAW. THIS SUPPLEMENTAL INDENTURE SHALL BE GOVERNED BY AND
CONSTRUED IN ACCORDANCE WITH THE LAWS OF THE STATE OF NEW YORK BUT WITHOUT
GIVING EFFECT TO APPLICABLE PRINCIPLES OF CONFLICTS OF LAW TO THE EXTENT THAT
THE APPLICATION OF THE LAWS OF ANOTHER JURISDICTION WOULD BE REQUIRED THEREBY.

         3.6 FULL FORCE AND EFFECT. The Indenture, as supplemented by this
Supplemental Indenture, remains in full force and effect and is hereby ratified
and confirmed as the valid and binding obligation of the parties hereto.


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         3.7 TRUSTEE. The Trustee accepts the modifications of trusts referenced
in the Indenture and effected by this Supplemental Indenture. Without limiting
the generality of the foregoing, the Trustee assumes no responsibility for the
correctness of the recitals herein contained, which shall be taken as the
statements of the Company and the Subsidiary Guarantors, and the Trustee shall
not be responsible or accountable in any way whatsoever for or with respect to
the validity or execution or sufficiency of this Supplemental Indenture, and the
Trustee makes no representation with respect thereto.

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         IN WITNESS WHEREOF, the parties hereto have executed this Supplemental
Indenture as of the date first above written.

EL PASO ENERGY PARTNERS,                EL PASO ENERGY PARTNERS
L.P.                                    FINANCE CORPORATION


By: /s/ KEITH FORMAN                    By: /s/ KEITH FORMAN
   -----------------------------           ------------------------------------
Name:  Keith Forman                     Name:  Keith Forman
Title: Chief Financial Officer          Title: Chief Financial Officer


CHASE BANK OF TEXAS,
NATIONAL ASSOCIATION, as Trustee


By: /s/ MAURI J. COWEN
   -------------------------------------
Name: Mauri J. Cowen
     -----------------------------------
Title: Vice President and Trust Officer
      ----------------------------------

NEW GUARANTOR:

GREEN CANYON PIPE LINE COMPANY, L.P.


By: /s/ KEITH FORMAN
   -----------------------------
Name:  Keith Forman
Title: Chief Financial Officer

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Each of the undersigned hereby ratifies and confirms its respective obligations
under the Indenture, as supplemented by this Supplemental Indenture:

                              DELOS OFFSHORE COMPANY, L.L.C.
                              EWING BANK GATHERING COMPANY, L.L.C.
                              EL PASO ENERGY PARTNERS DEEPWATER, L.L.C.
                              EL PASO ENERGY PARTNERS OIL TRANSPORT, L.L.C.
                              EL PASO ENERGY PARTNERS OPERATING COMPANY, L.L.C.
                              FLEXTREND DEVELOPMENT COMPANY, L.L.C.
                              MANTA RAY GATHERING COMPANY, L.L.C.
                              MORAY PIPELINE COMPANY, L.L.C.
                              POSEIDON PIPELINE COMPANY, L.L.C.
                              SAILFISH PIPELINE COMPANY, L.L.C.
                              TARPON TRANSMISSION COMPANY
                              VK DEEPWATER GATHERING COMPANY, L.L.C.
                              VK-MAIN PASS GATHERING COMPANY, L.L.C.


                              By: /s/ KEITH FORMAN
                                 ----------------------------------------------
                              Name:  Keith Forman
                              Title: Chief Financial Officer of Each Such Entity