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                                                                    Exhibit 4.12

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                        HORNBECK OFFSHORE SERVICES, INC.

                                       AND

                           THE GUARANTOR NAMED HEREIN

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                                    SERIES B

                          10 5/8% SENIOR NOTES DUE 2008

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                          SECOND SUPPLEMENTAL INDENTURE

                      AND AMENDMENT - SUBSIDIARY GUARANTEE

                            Dated as of June 18, 2003


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


                WELLS FARGO BANK MINNESOTA, NATIONAL ASSOCIATION

                                     Trustee


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     This SECOND SUPPLEMENTAL INDENTURE AND AMENDMENT - SUBSIDIARY GUARANTEE
("Supplemental Indenture"), dated as of June 18, 2003, is among Hornbeck
Offshore Services, Inc., a Delaware corporation (the "Company"), HOS-IV, LLC
(the "New Guarantor") and Wells Fargo Bank Minnesota, National Association, a
national banking association, as Trustee.

                                    RECITALS

     WHEREAS, the Company originally issued $175,000,000 aggregate principal
amount of 10 5/8% Senior Notes due 2008 (the "Notes") under the terms of that
certain Indenture, dated as of July 24, 2001 (the "Original Indenture"), by and
between the Company, the Trustee, and the subsidiary guarantors named therein;
and

     WHEREAS, the Original Indenture was supplemented and amended in order to
name additional subsidiaries of the Company as subsidiary guarantors of the
Notes under the terms of that certain Supplemental Indenture and Amendment -
Subsidiary Guarantee, dated as of December 17, 2001, by and between the Company,
the Trustee and the additional subsidiary guarantors named therein (the "First
Supplement"); and

     WHEREAS, the Original Indenture, as supplemented by the First Supplement,
shall hereinafter be referred to as the "Indenture"; and

     WHEREAS, Section 9.01(f) of the Indenture provides that the Indenture may
amended or supplemented in order to add any new guarantor of the Indenture to
comply with Section 10.02 thereof, without the consent of the Holders of the
Notes; and

     WHEREAS, all acts and things prescribed by the Indenture, by law and by the
charter and the bylaws (or comparable constituent documents) of the Company, of
the New Guarantor and of the Trustee necessary to make this Supplemental
Indenture a valid instrument legally binding on the Company, the New Guarantor
and the Trustee, in accordance with its terms, have been duly done and
performed;

     NOW, THEREFORE, to comply with the provisions of the Indenture and in
consideration of the above premises, the Company, the New Guarantor and the
Trustee covenant and agree for the equal and proportionate benefit of the
respective Holders of the Notes as follows:

                                   ARTICLE 1

     Section 1.01. This Supplemental Indenture is supplemental to the Indenture
and does and shall be deemed to form a part of, and shall be construed in
connection with and as part of, the Indenture for any and all purposes.

     Section 1.02. This Supplemental Indenture shall become effective
immediately upon its execution and delivery by each of the Company, the New
Guarantor and the Trustee.

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                                    ARTICLE 2

     Section 2.01. From this date, in accordance with Section 10.02 and by
executing this Supplemental Indenture and a notation of Subsidiary Guarantee (a
copy of which is attached hereto), the New Guarantor whose signature appears
below is subject to the provisions of the Indenture to the extent provided for
in Article 10 thereunder.

                                    ARTICLE 3

     Section 3.01. Except as specifically modified herein, the Indenture and the
Notes are in all respects ratified and confirmed (mutatis mutandis) and shall
remain in full force and effect in accordance with their terms with all
capitalized terms used herein without definition having the same respective
meanings ascribed to them as in the Indenture.

     Section 3.02. Except as otherwise expressly provided herein, no duties,
responsibilities or liabilities are assumed, or shall be construed to be
assumed, by the Trustee by reason of this Supplemental Indenture. This
Supplemental Indenture is executed and accepted by the Trustee subject to all
the terms and conditions set forth in the Indenture with the same force and
effect as if those terms and conditions were repeated at length herein and made
applicable to the Trustee with respect hereto.

     Section 3.03. THE LAW OF THE STATE OF NEW YORK SHALL GOVERN AND BE USED TO
CONSTRUE AND ENFORCE THIS SUPPLEMENTAL INDENTURE.

     Section 3.04. The parties may sign any number of copies of this
Supplemental Indenture. Each signed copy shall be an original, but all of such
executed copies together shall represent the same agreement.

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     IN WITNESS WHEREOF, the parties hereto have caused this Supplemental
Indenture to be duly executed, all as of the date first written above.

                        COMPANY:

                        HORNBECK OFFSHORE SERVICES, INC.

                        By: /s/ James O. Harp, Jr.
                           ----------------------------------------------------
                           James O. Harp, Jr.
                           Vice President and Chief Financial Officer

                        TRUSTEE:

                        WELLS FARGO BANK MINNESOTA,
                        NATIONAL ASSOCIATION

                        By: /s/ Nedine A. Peluso
                           ----------------------------------------------------
                           Name: Nedine A. Peluso
                           Title: Corporate Trust Offices

                        NEW GUARANTOR:

                        HOS-IV, LLC,



                        By: /s/ James O. Harp, Jr.
                           ----------------------------------------------------
                           James O. Harp, Jr.
                           Vice President and Chief Financial Officer

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                        NOTATION OF SUBSIDIARY GUARANTEE

     Subject to Section 10.06 of the Indenture, each Guarantor has jointly and
severally, unconditionally guaranteed 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 and
the Obligations of the Company under the Notes or under the Indenture, that: (a)
the principal of and premium, if any, interest and Liquidated Damages, if any,
on the Notes will be promptly paid in full when due, subject to any applicable
grace period, whether at maturity, by acceleration, redemption or otherwise, and
interest on overdue principal of and premium, if any, (to the extent permitted
by law) interest and Liquidated Damages, if any, on the Notes and all other
payment Obligations of the Company to the Holders or the Trustee under the
Indenture or under the Notes will be promptly paid in full and performed, all in
accordance with the terms thereof; and (b) in case of any extension of time of
payment or renewal of any Notes or any of such other payment Obligations, the
same will be promptly paid in full when due or performed in accordance with the
terms of the extension or renewal, subject to any applicable grace period,
whether at stated maturity, by acceleration, redemption or otherwise. Failing
payment when so due of any amount so guaranteed or any performance so guaranteed
for whatever reason, the Guarantors will be jointly and severally obligated to
pay the same immediately. An Event of Default under the Indenture or the Notes
shall constitute an event of default under the Subsidiary Guarantees, and shall
entitle the Holders to accelerate the obligations of the Guarantors under the
Indenture in the same manner and to the same extent as the Obligations of the
Company. The Guarantors have agreed that their Obligations 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 with respect to any
provisions hereof or thereof, the recovery of any judgment against the Company,
any action to enforce the same or any other circumstance which might otherwise
constitute a legal or equitable discharge or defense of a Guarantor. Each
Guarantor further, to the extent permitted by law, has waived diligence,
presentment, demand of payment, filing of claims with a court in the event of
insolvency or bankruptcy of the Company, any right to require a proceeding first
against the Company, protest, notice and all demands whatsoever and covenants
that its Subsidiary Guarantee will 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
Company, the Guarantors, or any Note Custodian, Trustee, liquidator or other
similar official acting in relation to either the Company or the Guarantors, any
amount paid by the Company or any Guarantor to the Trustee or such Holder, the
Subsidiary Guarantees, to the extent theretofore discharged, shall be reinstated
in full force and effect. Each Guarantor has agreed that it shall not be
entitled to, and hereby has waived, any right of subrogation in relation to the
Holders in respect of any Obligations guaranteed under the Indenture. Each
Guarantor further has agreed that, as between the Guarantors, on the one hand,
and the Holders and the Trustee, on the other hand, (a) the maturity of the
Obligations guaranteed under the Indenture may be accelerated as provided in
Article 6 of the Indenture for the purposes of its Subsidiary Guarantee,
notwithstanding any stay, injunction or other prohibition preventing such
acceleration in respect of the Obligations guaranteed thereby, and (b) 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 Guarantor for the purpose of its
Subsidiary Guarantee. The Guarantors shall have the right to seek contribution
from any non-paying Guarantor so long as the

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exercise of such right does not impair the rights of the Holders under the
Subsidiary Guarantees.

     The obligations of the Guarantors to the Holders and to the Trustee
pursuant to the Subsidiary Guarantees and the Indenture are expressly set forth
in Article 10 of the Indenture, and reference is hereby made to such Indenture
for the precise terms of the Subsidiary Guarantees. The terms of Article 10 of
the Indenture are incorporated herein by reference. The Subsidiary Guarantees
are subject to release as and to the extent provided in Sections 10.04 and 10.05
of the Indenture.

     Each Subsidiary Guarantee is a continuing guarantee and shall remain in
full force and effect and shall be binding upon each Guarantor and its
respective successors and assigns to the extent set forth in the Indenture until
full and final payment of all of the Company's Obligations under the Notes and
the Indenture and shall inure to the benefit of the successors and assigns of
the Trustee and the Holders and, in the event of any transfer or assignment of
rights by any Holder or the Trustee, the rights and privileges conferred in the
Indenture upon that party shall automatically extend to and be vested in such
transferee or assignee, all subject to the terms and conditions hereof. Each
Subsidiary Guarantee is a guarantee of payment and not a guarantee of
collection.

     For purposes hereof, each Guarantor's liability under its Subsidiary
Guarantee shall be limited in amount as provided in Section 10.06 of the
Indenture.

     Capitalized terms used herein have the same meanings given in the Indenture
unless otherwise indicated.

                                   GUARANTOR:

                                   HOS-IV, LLC


                                   By: /s/ James O. Harp, Jr.
                                      -----------------------------------------
                                      James O. Harp, Jr.
                                      Vice President and Chief Financial Officer


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