SECOND SUPPLEMENTAL INDENTURE

Exhibit 4.3

NOBLE CORPORATION,
ISSUER,

NOBLE DRILLING CORPORATION,
GUARANTOR,

NOBLE HOLDING INTERNATIONAL LIMITED,
GUARANTOR,

AND

THE BANK OF NEW YORK MELLON TRUST COMPANY, N.A.,
TRUSTEE

SECOND SUPPLEMENTAL INDENTURE

RELATING TO

$300,000,000 of 5.875% Senior Notes due 2013

Dated as of October 1, 2009

          SECOND SUPPLEMENTAL INDENTURE, dated as of October 1, 2009 (this “ Second Supplemental Indenture ”), by and among NOBLE CORPORATION, a Cayman Islands exempted company limited by shares (herein called the “ Company ”), NOBLE DRILLING CORPORATION, a Delaware corporation and a wholly-owned indirect subsidiary of the Company (herein called “ Noble Drilling ”), NOBLE HOLDING INTERNATIONAL LIMITED, a Cayman Islands exempted company limited by shares (herein called “ NHIL ” and, together with Noble Drilling, the “ Guarantors ”), and THE BANK OF NEW YORK MELLON TRUST COMPANY, N.A., a national banking association duly organized and existing under the laws of the United States of America, successor by merger to JPMorgan Chase Bank, National Association, as Trustee (herein called the “ Trustee ”).

WITNESSETH:

          WHEREAS, the Company has previously executed and delivered to the Trustee an indenture dated as of May 26, 2006, as supplemented by the First Supplemental Indenture thereto dated as of May 26, 2006 (the “ First Supplemental Indenture ”; the indenture, as supplemented by the First Supplemental Indenture, the “ Supplemented Indenture ”), providing for the issuance from time to time of its unsecured senior debt securities (the “ Securities ”);

          WHEREAS, the Company has issued, and the Trustee has authenticated and delivered, a series of Securities designated the “5.875% Senior Notes due 2013” (the “ Notes ”);

          WHEREAS, the Company is the obligor with respect to the Notes;

          WHEREAS, pursuant to Section 3 of the First Supplemental Indenture, Noble Drilling has irrevocably and unconditionally guaranteed the due and punctual payment of the principal of, premium, if any, interest on and all other amounts due under, the Indenture and the Notes; and

          WHEREAS, as part of an internal reorganization, NHIL will acquire an indirect interest in all but three drilling rigs previously owned directly or indirectly by Noble Drilling (the “ Asset Transfer ”);

          WHEREAS, Section 901(9) of the Supplemented Indenture provides that, without the consent of any Holders, the Company, when authorized by a Board Resolution, and the Trustee, at any time and from time to time, may enter into one or more indentures supplemental to the Supplemented Indenture, to make any provisions with respect to matters arising under the Supplemented Indenture, provided such provisions shall not adversely affect the interests of the Holders of Securities of any series in any material respect;

          WHEREAS, the Company and the Guarantors, pursuant to the foregoing authority, propose to amend and supplement the Supplemented Indenture in certain respects to evidence NHIL’s agreement to fully and unconditionally guarantee the due and punctual payment of the principal of, premium, if any, interest on and all other amounts due under the Supplemented Indenture and the Notes, which guarantee is provided in this Second Supplemental Indenture; and

          WHEREAS, all things necessary to make this Second Supplemental Indenture a valid and legally binding supplemental indenture to the Supplemented Indenture (the Supplemented Indenture, as further supplemented by this Second Supplemental Indenture, the “ Indenture ”) in accordance with the terms thereof have been done, and the execution and delivery of this Second Supplemental Indenture have been duly authorized in all respects;

          NOW, THEREFORE, in consideration of the promises and mutual agreements herein contained, the Company, the Guarantors and the Trustee mutually covenant and agree for the equal and proportionate benefit of the Holders from time to time of the Notes as follows:

     SECTION 1. AGREEMENT TO GUARANTEE

          NHIL hereby agrees as follows:

          (a) Subject to Subsection 1(b) below, NHIL (or any successor person pursuant to the applicable provisions of this Second Supplemental Indenture) hereby irrevocably and unconditionally guarantees (such guarantee being the “Guarantee”) 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 and the Notes, that: (i) the principal of, premium, if any, and interest on the Notes promptly will be paid in full when due, whether at the Maturity, by acceleration, call for redemption or otherwise, and interest on the overdue principal, premium, if any, and interest, if any, on the Notes, if lawful, and all other payment obligations of the Company to the Holders and the Trustee under the Indenture and the Notes will be promptly paid in full, all in accordance with the terms of the Indenture and the Notes, and (ii) 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 in accordance with the terms of the extension or renewal, whether at Stated Maturity, by acceleration or otherwise. Failing payment when due by the Company of any amount so guaranteed for whatever reason, NHIL shall be obligated to pay the same immediately. NHIL hereby agrees that its obligations hereunder shall be unconditional, irrespective of the validity, regularity or enforceability of the Indenture or the Notes, 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 or the Notes, the recovery of any judgment against the Company, or any action to enforce the same or any other circumstance which might otherwise constitute a legal or equitable discharge or defense of a guarantor. NHIL hereby waives presentment, demand of payment, protest, notice and all demands whatsoever and covenants that this Guarantee shall not be discharged except by complete performance of the obligations contained in the Notes and the Indenture.

          (b) It is the intention of NHIL and the Company that the obligations of NHIL hereunder shall be, but not in excess of, the maximum amount permitted by applicable law. Accordingly, if the obligations in respect of the Guarantee would be annulled, avoided or subordinated to the creditors of NHIL by a court of competent jurisdiction in a proceeding actually pending before such court as a result of a determination both that such Guarantee was made without fair consideration and, immediately after giving effect thereto, NHIL was insolvent or unable to pay its debts as they mature or left with an unreasonably small capital, then the obligations of NHIL under the Guarantee shall be reduced by such court if such reduction would result in the avoidance of such annulment, avoidance or subordination; provided, however, that

any reduction pursuant to this paragraph shall be made in the smallest amount as is strictly necessary to reach such result. For purposes of this paragraph, “fair consideration,” “insolvency,” “unable to pay its debts as they mature,” “unreasonably small capital” and the effective times of reductions, if any, required by this paragraph shall be determined in accordance with applicable law.

          (c) NHIL shall be subrogated to all rights of the Holders against the Company in respect of any amounts paid by NHIL pursuant to the provisions of the Guarantee or the Indenture; provided, however, that NHIL shall not be entitled to enforce or to receive any payments arising out of, or based upon, such right of subrogation until the principal of, premium, if any, and interest on all Notes issued under the Indenture shall have been paid in full.

     SECTION 2. EXECUTION AND DELIVERY OF GUARANTEE

          To evidence the Guarantee set forth in Section 1, the Company and NHIL hereby agree that a notation of such Guarantee shall be endorsed on each Note hereafter authenticated and delivered by the Trustee, that such notation of such Guarantee shall be in the form attached hereto as Exhibit A , and shall be executed on behalf of NHIL by an officer thereof.

          NHIL hereby agrees that the Guarantee set forth in Section 1 shall remain in full force and effect notwithstanding any failure to endorse on each Note a notation of the Guarantee.

     SECTION 3. RELEASE OF NHIL

          NHIL shall be released from all of its obligations under the Guarantee and under the Indenture if:

          (a) the