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Exhibit 2.1
 
 AGREEMENT AND PLAN OF MERGER
 DATED AS OF JUNE 11, 2007
 BY AND AMONG
 CAL DIVE INTERNATIONAL, INC.,
 CAL DIVE ACQUISITION, LLC
 AND
 HORIZON OFFSHORE, INC.




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TABLE OF CONTENTS
 PageARTICLE I THE MERGER
    
    
    11.1 The Merger
    
    
    11.2 Effective Time of the Merger
    
    
    11.3 Effects of the Merger
    
    
    11.4 Closing
    
    
    11.5 Certificate of Formation
    
    
    21.6 Limited Liability Company Agreement
    
    
    21.7 Managers and Officers
    
    
    2ARTICLE II CONSIDERATION/ EXCHANGE PROCEDURES
    
    
    22.1 Effect of the Merger on Capital Stock
    
    
    22.2 Dissenting Shares
    
    
    32.3 Stock Options and Equity Awards
    
    
    42.4 Surrender and Payment
    
    
    52.5 No Fractional Shares
    
    
    92.6 Lost Certificates
    
    
    92.7 Withholding Rights
    
    
    92.8 No Further Ownership Rights in Company Common Stock
    
    
    92.9 Investment of Cash by the Exchange Agent
    
    
    92.10 Further Assurances
    
    
    102.11 Shares Held by Company Affiliates
    
    
    10ARTICLE III REPRESENTATIONS AND WARRANTIES
    
    
    103.1 Representations and Warranties of the Company
    
    
    103.2 Representations and Warranties of Cal Dive
    
    
    24ARTICLE IV COVENANTS RELATING TO CONDUCT OF BUSINESS
    
    
    374.1 Covenants of the Company
    
    
    374.2 Covenants of Cal Dive
    
    
    394.3 Governmental Filings
    
    
    414.4 No Control of Other Partys Business
    
    
    42ARTICLE V ADDITIONAL AGREEMENTS
    
    
    425.1 Preparation of Information Statement/Proxy Statement/Prospectus;
Stockholders Meeting
    
    
    425.2 Access to Information
    
    
    445.3 Required Actions
    
    
    455.4 Acquisition Proposals
    
    
    465.5 Fees and Expenses
    
    
    495.6 Directors and Officers Indemnification and Insurance
    
    
    495.7 Employee Benefits; Retention Plan
    
    
    505.8 Public Announcements
    
    
    515.9 Listing of Shares of Cal Dive Common Stock
    
    
    51
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TABLE OF CONTENTS
 Page5.10 Affiliates
    
    
    515.11 Section 16 Matters
    
    
    515.12 Tax Matters
    
    
    515.13 Vessel Matters
    
    
    52ARTICLE VI CONDITIONS PRECEDENT
    
    
    526.1 Conditions to Each Partys Obligation to Effect the Merger
    
    
    526.2 Additional Conditions to Obligations of Cal Dive
    
    
    526.3 Additional Conditions to Obligations of the Company
    
    
    53ARTICLE VII TERMINATION
    
    
    547.1 Termination
    
    
    547.2 Effect of Termination
    
    
    55ARTICLE VIII CERTAIN DEFINITIONS
    
    
    56ARTICLE IX GENERAL PROVISIONS
    
    
    679.1 Non-Survival of Representations, Warranties and Agreements
    
    
    679.2 Notices
    
    
    679.3 Interpretation
    
    
    689.4 Counterparts
    
    
    699.5 Entire Agreement; No Third Party Beneficiaries
    
    
    699.6 Governing Law
    
    
    699.7 Severability
    
    
    699.8 Assignment
    
    
    709.9 Submission to Jurisdiction; Waivers
    
    
    709.10 Enforcement
    
    
    709.11 Amendment
    
    
    709.12 Extension; Waiver
    
    
    70
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LIST OF EXHIBITS
 Exhibit
    
    TitleExhibit A
    
    Form of Affiliate Agreement
 iii




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Agreement Cal Dive Merger Sub Company
 W I T N E S S E T H:
 Merger Surviving Company
 Plan of Merger
   ARTICLE I
 THE MERGER
 The Merger
 Effective Time of the Merger Certificate of Merger Effective Time
 Effects of the Merger
 Closing Closing Article VI




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Closing Date
 Certificate of Formation
 Limited Liability Company Agreement
 Managers and Officers
 ARTICLE II
 CONSIDERATION/ EXCHANGE PROCEDURES
 Effect of the Merger on Capital Stock
 Article II Section 2.2 Merger Consideration
 Per Share Cash Amount Exchange Ratio Section
2.1(c)
 Article II Certificate Section 2.5
 -2-




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Section 2.1(d)
  Dissenting Shares Dissenting
Share Section 262 Section 262 Section 262
 -3-




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Stock Options and Equity Awards
 Company Stock Option Converted Cal Dive Option Section 2.3 Section 2.3(a)
  Section 2.3 Section 2.3
 -4-




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Surrender and Payment
 Exchange Agent Section
2.1(a) Section 2.3(a) (b), Section 2.5 Section 2.5 Exchange Fund.
 Section 2.1 Section 2.1 Article II Section 2.5
  -5-




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Article II
 Section 2.4
 Section 2.4
 No Fractional Shares Section 2.4
 Lost Certificates Article II
 Withholding Rights Article II
 -6-




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No Further Ownership Rights in Company Common Stock Article II Section 2.4 2.5
 Investment of Cash by the Exchange Agent Article II
 Further Assurances
 Shares Held by Company Affiliates Section
5.10) Section 5.10
 ARTICLE III
 REPRESENTATIONS AND WARRANTIES
 Representations and Warranties of the Company Section 9.3(a) Sections 3.1(f) (o)
 Corporate Organization
  -7-




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Capitalization
 .
 -8-




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Section 3.1(b) Section 3.1(b) Section 3.1(e)(v)
 Authority; No Violation
 Company Stockholders
Meeting Company Stockholder Approval
  -9-




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Section 3.1(d)
 Consents and Approvals Information Statement/Proxy
Statement/Prospectus Company Necessary Consents
 Financial Reports and SEC Documents
  -10-




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Company SEC Documents
  -11-




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Section 3.1(e)(v) Section 3.1(e)(v)
 Absence of Undisclosed Liabilities
 -12-




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Absence of Certain Changes or Events
    Section 5.7(b)
  Legal Proceedings Section 3.1(h)
 -13-




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Compliance with Applicable Law
 Environmental Liability
 Employee Benefit Plans; Labor Matters
 Section 3.1(k)
 -14-




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-15-




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Section 3.1(k) Section 3.1(k)
 Section 3.1(k)
 Taxes
  -16-




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Contracts
 -17-




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Section 3.1(m) Company Contract
  Title to Properties
 Section 3.1(c)(v)
 -18-




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Insurance Section 3.1(o)
 Reorganization under the Code Sections 6.2(c) 6.3(c)
 State Takeover Statutes; Absence of Supermajority Provision.
 Opinion of Financial Advisor
 Board Approval
 Brokers Fees
 -19-




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Ownership of Cal Dive Capital Stock
 Vessel Related Matters
 Section 3.1(v)(i)(A)(I)
          -20-




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Certain Business Practices
 Representations and Warranties of Cal Dive Section 9.3(a) Sections 3.2(f) (m)
 Corporate Organization
    Capitalization
 -21-




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Section 3.2(b)(i)
 Section 3.2(b)(ii) Section 3.2(b)(ii)
 Authority; No Violation
 -22-




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Section 3.2(d)
 Consents and Approvals Form S-4
 -23-




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Cal Dive Necessary Consents
 Financial Reports and SEC Documents
 Cal
Dive SEC Documents
  -24-




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Section 3.2(e)(v) Section 3.2(e)(v)
 -25-




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Absence of Undisclosed Liabilities .
 Absence of Certain Changes or Events
    Section 3.2(b)(i)
 -26-




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Legal Proceedings Section 3.2(h)
 Compliance with Applicable Law
 Environmental Liability
 Employee Benefit Plans; Labor Matters
 -27-




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Section 3.2(k)
     -28-




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Taxes
  -29-




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Contracts
  -30-




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Section 3.2(m) Cal Dive Contract
  Title to Properties
 Section 3.2(n) Section 3.2(n)
  -31-




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Insurance Section 3.2(o)
 Reorganization under the Code Sections 6.2(c) 6.3(c)
 Opinion of Financial Advisors
 Board and Stockholder Approval
 Brokers Fees
 Vessel Related Matters.
 Section 3.2(t)(i)(A)(I)
   -32-




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Certain Business Practices
 Ownership of Company Capital Stock
 Funds
 -33-




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ARTICLE IV
 COVENANTS RELATING TO CONDUCT OF BUSINESS
 Covenants of the Company Section 4.1
 Ordinary Course
  Company Capital Budget
 Dividends; Changes in Share Capital
 Issuance of Securities
 -34-




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Section 4.1(f)
 Governing Documents
 No Acquisitions
 No Dispositions
 Investments; Indebtedness Section 4.1(e)
 Tax-Free Qualification
 -35-




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Sections 6.2(c) 6.3(c) Section 4.1
 Certain Actions Sections 5.4 7.1
 Related Actions
 Covenants of Cal Dive
 Section
4.2
 Ordinary Course
 Dividends; Changes in Share Capital
 -36-




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Issuance of Securities  Section
4.2(a)(vi)
 Governing Documents
 No Acquisitions
 No Dispositions
 Investments; Indebtedness
 -37-




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Section 4.2(a)(iv)
 Tax-Free Qualification Sections 6.2(c) 6.3(c) Section 4.2) Section
6.2(c)
 Certain Actions Section 7.1
 Related Actions
  Governmental Filings
 No Control of Other Partys Business
 -38-




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ARTICLE V
 ADDITIONAL AGREEMENTS
 Preparation of Information Statement/Proxy Statement/Prospectus; Stockholders
Meeting
  -39-




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-40-




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Section 3.1(s) Company Board Recommendation Section 5.4 Change in the Company Board Recommendation
 Access to Information
 -41-




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Required Actions
 Required Approvals
 Section 5.3(a)
 -42-




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Sections 5.3(a) 5.3(b) Section 6.1(a) Section 5.3(a) Section 5.3(c)
  Acquisition Proposals
 Company Representatives )
 -43-




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Section 5.4 Section 7.1(h)
 Section 5.4 Article VII
 Section 5.4 Section 5.4
 -44-




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Section
5.4(a) Section 5.4(c) Section 5.4(d)
 Section 5.4(d) Section 5.4(e) Section 5.4 Section
7.1(h) Section 7.2(b)(i)
 -45-




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Section 7.1(h) Section 7.2(b)(i)
 Fees and Expenses Section 7.2
 Directors and Officers Indemnification and Insurance
  -46-




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Section
5.6 Section 5.6 Section 5.6 Section 5.6
 Employee Benefits; Retention Plan
 New Plans Old
Plans
  Public Announcements
 -47-




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Listing of Shares of Cal Dive Common Stock
 Affiliates Exhibit A Affiliate Agreement
 Section 16 Matters Article I Article II
 Tax Matters Section 6.2(c) Section 6.3(c)
 Vessel Matters
 -48-




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ARTICLE VI
CONDITIONS PRECEDENT
 Conditions to Each Partys Obligation to Effect the Merger
 No Injunctions or Restraints; Illegality
 HSR Act; Other Approvals
 NYSE Listing
 Effectiveness of the Form S-4
 Stockholder Approval
 Additional Conditions to Obligations of Cal Dive
 Representations and Warranties
 -49-




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Section 6.2(a)
 Performance of Obligations of the Company
 Tax Opinion Section 5.12
 Additional Conditions to Obligations of the Company
 Representations and Warranties Section 6.3(a)
 Performance of Obligations of Cal Dive
 Tax Opinion
 -50-




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Section 5.12
 ARTICLE VII
TERMINATION
 Termination
  Section 7.1(b) Section 5.3)
 Sections 6.1(b) 6.1(c) 6.1(d) Section 7.1(c) Section 5.3
  Section 5.1, Section 7.1(h) Section
5.4
 -51-




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Section 6.2(a) 6.2(b)
 Section 6.3(a) 6.3(b)
 Section 5.4(d)
 Effect of Termination
 Section 7.1 Section 5.2 Section
5.5 Section 7.2 Article IX Section 7.2(b)(i) (ii) (iii)
 Section 7.1(h) Section 7.2(b)(i)
 Section 7.1(e) Section 7.2(b)(i)
 -52-




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Section 7.1(d) Section 7.1(f) Section 7.1(f) Section 7.2(b)(iii)(A) Section 7.1(b)(iii)
 Section 7.2 Section
7.2 Section 7.2 Section 5.5 Section 7.2
 ARTICLE VIII
CERTAIN DEFINITIONS
  Acceptable Confidentiality Agreement  Section 5.4
 -53-




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Acquisition Proposal
 Affiliate
 Affiliate Agreement Section 5.10
 Agreement
 Antitrust Laws
 Beneficial ownership beneficially own
 Benefit Plan
 Business Day
 Cal Dive
 Cal Dive Benefit Plan
 Cal Dive Capital Stock
 -54-




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Cal Dive Common Stock
 Cal Dive Contract Section 3.2(m)(i)
 Cal Dive Current 10-Q
 Cal Dive Disclosure Schedule
 Cal Dive ERISA Affiliate
 Cal Dive Necessary Consents Section 3.2(d)
 Cal Dive Preferred Stock
 Cal Dive SEC Documents Section 3.2(e)(i)
 Cal Dive Stock Plans
 Cal Dive Vessel Section
3.2(t)(i)(A)(I)
 CERCLA
 Certificate Section 2.1(c)
 Certificate of Merger Section 1.2
 Change in the Company Board Recommendation Section
5.1(f)
 Classification Society
 Closing Section 1.4
 Closing Date Section 1.4
 Code
 Company
 -55-




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Company Benefit Plan
 Company Board Recommendation Section 5.1(f)
 Company Capital Budget Section 4.1(a)(ii)
 Company Capital Stock
 Company Common Stock
 Company Contract Section 3.1(m)(i)
 Company Current 10-Q
 Company Disclosure Schedule
 Company Employees
 Company ERISA Affiliate
 Company Necessary Consents Section 3.1(d)
 Company Preferred Stock
 Company Representatives Section 5.4(a)
 Company SEC Documents Section 3.1(e)(i)
 Company Stock Option Section 2.3(a)
 Company Stock Plans
 Company Stockholder Approval Section 3.1(c)(i)
 -56-




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Company Stockholders Meeting Section 3.1(c)(i)
 Company Vessel Section 3.1(v)(i) Gulf Horizon
 Confidentiality Agreement
 Converted Cal Dive Option Section 2.3(a)
 Country of Registry
 DGCL
 DLLCA
 Dissenting Share Section 2.2
 DOJ
 Effective Time Section 1.2
 Environmental Claims
 Environmental Laws et seq et seq. et seq et seq.
 -57-




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et seq. et seq. et seq. et seq. et seq. et seq.
 Environmental Permits
 ERISA
 Event of Loss
 Exception Shares
 Exchange Act
 Exchange Agent Section 2.4(a)
 Exchange Fund Section 2.4(a)
 Exchange Ratio Section 2.1(a)
 Excluded Party
 Excluded Party Superior Proposal
 Expenses
 -58-




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 Form S-4  Section 3.1(d)
 FTC
 GAAP
 Governmental Entity
 Hazardous Materials
 Helix
 HSR Act
 Indebtedness
 Information Statement/Proxy Statement/Prospectus Section 3.1(d)
 Knowledge Known
 Liens
 Mailing Date Section 2.4(b)
 -59-




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Market Price
 Material Adverse Effect
 Merger Consideration Section 2.1(a)
 Merger
 Merger Sub
 Multiemployer Plan
 Nasdaq Global Market
 New Plans Section 5.7
 No-Shop Period Start Date
 NYSE
 Old Plans Section 5.7
 Other Party
 Party
 Pension Plan
 Per Share Cash Amount Section 2.1(a)
 -60-




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Permitted Liens
 Person
 Plan of Merger
 Qualifying Amendment
 Regulatory Law
 Release
 Required Approvals Section 5.3(a)
 Sarbanes-Oxley Act
 SEC
 -61-




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Securities Act
 Stock Award Exchange Ratio
 Subsidiary
 Superior Proposal
 Surviving Company
 Tax Return
 Taxes
 Termination Date
 Termination Fee
 Vessel(s) Section 3.1(v)(i) Gulf Horizon Section
 -62-




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3.2(t)(i)(A)(I)
 Voting Debt
 ARTICLE IX
 GENERAL PROVISIONS
 Non-Survival of Representations, Warranties and Agreements Article IX Section 5.6
 Notices
 (a)
    
    if to Cal Dive:Cal Dive International, Inc. 
400 N. Sam Houston Parkway E., Suite 400
Houston, Texas 77060
Facsimile: (281) 848-6502Attention: General Counselwith a copy to (which shall not constitute notice):Fulbright & Jaworski L.L.P.Fulbright Tower1301 McKinney, Suite 5100Houston, Texas 77010Facsimile: (713) 651-5246Attention: David Peterman(b)
    
    if to the Company to:Horizon Offshore, Inc.2500 City West Blvd.Suite 2200Houston, Texas 77042
 -63-




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Facsimile: (713) 361-2693Attention: General Counselwith a copy to (which shall not constitute notice):Jones, Walker, Waechter, Poitevent, Carrere & Denegre, L.L.P.201 St. Charles Ave., Suite 5100New Orleans, Louisiana 70170Facsimile: 504-582-8012Attention: William B. Masters
 Interpretation
   Counterparts
 Entire Agreement; No Third Party Beneficiaries
  -64-




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Section 5.6
 Governing Law
 Severability
 Assignment
 Submission to Jurisdiction; Waivers
 -65-




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Enforcement
 Amendment
 Extension; Waiver
 -66-




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IN WITNESS WHEREOF,
 CAL DIVE INTERNATIONAL, INC.By:
    
    /s/ Quinn J. Hebert

Quinn J. Hebert
President and Chief Executive OfficerCAL DIVE ACQUISITION, LLCBy:
    
    /s/ Quinn J. HebertQuinn J. Hebert
Chairman and Chief Executive OfficerHORIZON OFFSHORE, INC.By:
    
    /s/ David W. SharpDavid W. Sharp
President and Chief Executive Officer




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Exhibit A
 FORM OF AFFILIATE AGREEMENT
 
  Company Rules and
Regulations Commission Securities Act Merger Agreement Cal Dive Merger Sub Cal Dive Common Stock Merger
     -1-




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Exchange
Act
 -2-




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Very truly yours,By:Name:
 
 CAL DIVE INTERNATIONAL, INC.
 By:Quinn J. Hebert
President and Chief Executive OfficerCAL DIVE ACQUISITION, LLCBy:Quinn J. Hebert
Chairman and Chief Executive OfficerHORIZON OFFSHORE, INC.By:David W. Sharp
President and Chief Executive Officer
 -3-