<PAGE>
                                                                    Exhibit 10.2

                                                               Execution Version

                                 March 14, 2006

Cedar Fair, L.P.
Knott's Berry Farm
One Cedar Point Drive
Sandusky, Ohio 44871
Attn: Corporate Vice President - Finance

     RE: MODIFICATION LETTER TO 1994/2004 SHELF AGREEMENTS OF CEDAR FAIR, L.P.

Ladies and Gentlemen:

     Reference is made to (i) that certain Amended and Restated Note Purchase
and Private Shelf Agreement, dated as of April 7, 2004 (as amended, modified and
supplemented prior to the date hereof, the "2004 Shelf Agreement") among Cedar
Fair, L.P., a Delaware limited partnership (the "Company"), and Knott's Berry
Farm, a California general partnership ("Knott's Berry Farm"; the Company and
Knott's Berry Farm are hereinafter collectively referred to as the "Co-Issuers"
and individually referred to as a "Co-Issuer"), on the one hand, and Prudential
Investment Management, Inc., The Prudential Insurance Company of America
("PICA"), Hartford Life Insurance Company, Medica Health Plan and each
Prudential Affiliate which is or which becomes a party to the 2004 Shelf
Agreement, on the other hand and (ii) that certain Private Shelf Agreement,
dated as of August 24, 1994 (as amended, modified and supplemented prior to the
date hereof, the "1994 Shelf Agreement"; and, collectively with the 2004 Shelf
Agreement, the "Shelf Agreements"), between the Company and PICA. Capitalized
terms used herein and not otherwise defined herein shall have the meanings
assigned to such terms in the Shelf Agreements (as hereby amended).

     Pursuant to the request of the Co-Issuers and in accordance with the
provisions of paragraph 11C of the Shelf Agreements, the parties hereto agree as
follows:

     SECTION 1. AMENDMENT. From and after the date this letter becomes effective
in accordance with its terms, each Shelf Agreement is amended as follows:

     1.1 Paragraph 5A of each Shelf Agreement is amended by inserting ", 6E"
after the reference to "6C" in the penultimate paragraph of 5A in each Shelf
Agreement.

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     1.2 Paragraph 5 of each Shelf Agreement is amended by adding a new
Paragraph 5L after Paragraph 5K of each Shelf Agreement to read as follows:

          "5L. EXCESS LEVERAGE FEE. In addition to interest accruing on the
     Notes, the Co-Issuers hereby agree to pay to the holder of each Note a fee
     (the "LEVERAGE FEE") with respect to each fiscal quarter of the Company
     (commencing with the fiscal quarter ending June 30, 2006), on the last day
     of which the ratio of Consolidated Debt to Consolidated EBITDA exceeds 3.25
     to 1.00. The amount of the Leverage Fee, if any, with respect to each Note
     shall be a dollar amount equal to the product obtained by multiplying (a)
     the Fee Factor as set forth in the table below opposite the applicable
     ratio of Consolidated Debt to Consolidated EBITDA as of the last day of
     such fiscal quarter by (b) the Weighted Dollar Average (as defined below)
     of the outstanding principal balance of such Note during such fiscal
     quarter.

<TABLE>
<CAPTION>
CONSOLIDATED DEBT / EBITDA   FEE FACTOR
--------------------------   ----------
<S>                          <C>
       3.26x - 3.30x          0.000125
       3.31x - 3.40x          0.00025
       3.41x - 3.50x          0.000375
       > 3.50x                0.000625
</TABLE>

          The Leverage Fee for any fiscal quarter shall otherwise be calculated
     on the same basis as interest on the Notes is calculated and shall be
     payable in arrears on the 60th day after the end of such fiscal quarter.
     The consequences for the failure to pay the Leverage Fee when due shall be
     governed by paragraph 7A(ii) of this Agreement treating the Leverage Fee,
     solely for such purposes, as interest. The payment of a Leverage Fee shall
     not constitute a waiver of any Default or Event of Default. As used in this
     paragraph, "Weighted Dollar Average" shall mean, with respect to any Note,
     during any fiscal quarter of the Company, a dollar amount determined by
     adding together the daily outstanding principal balance of such Note during
     such fiscal quarter and dividing the amount thus obtained by the total
     number of days during such fiscal quarter."

     1.3 Paragraph 6A(2) is amended by deleting the existing paragraph 6A(2) in
its entirety and replacing it with a new paragraph 6A(2) to read as follows:

          "6A(2). DEBT. Create, incur, assume, guarantee, suffer to exist, or
     otherwise be or become directly or indirectly liable for, any Funded or
     Current Debt, except

          (i) Funded Debt of the Company represented by the Notes,

          (ii) Funded or Current Debt of any Subsidiary to the Company,

          (iii) Funded or Current Debt of any Subsidiary to any other
     Subsidiary, provided that no Subsidiary shall become liable for or suffer
     to exist any Debt permitted


                                                                               2

<PAGE>

     by this clause (iii) unless the Subsidiary to which such Debt is owed shall
     be free from any Debt to any Person other than the Company, and

          (iv) other Debt of the Company or any Subsidiary; provided that
     Priority Debt shall at no time exceed 20% of Consolidated Owners Equity
     (notwithstanding the foregoing, the basket in this subclause (iv) shall not
     be used to secure the lender(s) under the Credit Agreement (or any credit
     facility which replaces the Credit Agreement) and if such other Debt is
     Funded Indebtedness, at the time of the creation, issuance, assumption,
     guaranty or incurrence thereof and after giving effect thereto and to the
     application of the proceeds thereof, (1) the ratio of (a) Consolidated
     Funded Indebtedness to (b) Consolidated Operating Cash Flow for the
     immediately preceding four fiscal quarter period shall not exceed 3.25 to
     1.00 and (2) no Default or Event of Default exists or will exist after
     giving effect thereto;

          The renewal, extension or refunding of any Funded Indebtedness,
     issued, incurred or outstanding pursuant to paragraph 6A(2) shall
     constitute the issuance of additional Funded Indebtedness which is, in
     turn, subject to the limitations of the applicable provisions of this
     paragraph 6A(2).

          For purposes of clause (iv) of this paragraph 6A(2), the following
     terms shall have the meanings specified with respect thereto below.

                    "CAPITALIZED LEASE" means any lease the obligation for
          Rentals with respect to which is required to be capitalized on a
          consolidated balance sheet of the lessee and its subsidiaries in
          accordance with GAAP.

                    "CAPITALIZED RENTALS" of any Person means as of the date of
          any determination thereof the amount at which the aggregate Rentals
          due and to become due under all Capitalized Leases under which such
          Person is a lessee would be reflected as a liability on a consolidated
          balance sheet of such Person.

                    "CONSOLIDATED FUNDED INDEBTEDNESS" means, without
          duplication, (a) all Funded Indebtedness of the Company and its
          Subsidiaries, determined on a consolidated basis eliminating
          intercompany items and (b) all Current Indebtedness of the Company and
          its Subsidiaries, determined on a consolidated basis eliminating
          intercompany items measured at the lowest aggregate principal amount
          of Current Indebtedness outstanding during any period of 10
          consecutive days within the 365 days immediately preceding the date of
          any determination hereunder.

                    "CONSOLIDATED INTEREST EXPENSE" means all Interest Expense
          of the Company and its Subsidiaries for any period after eliminating
          intercompany items.

                    "CONSOLIDATED NET EARNINGS" means, with reference to any
          period and without duplication, the net earnings (or loss) of the
          Company and its Subsidiaries for such period (taken as a cumulative
          whole), as determined in accordance with GAAP, after eliminating (a)
          extraordinary gains and losses and (b) net earnings of any business
          entity (other than a Subsidiary) in which the Company or any of its


                                                                               3

<PAGE>

          Subsidiaries has an ownership interest unless such net earnings shall
          have actually been received by the Company or such Subsidiary in the
          form of cash distributions.

                    "CONSOLIDATED OPERATING CASH FLOW" for any period means the
          total of (a) (i) Consolidated Net Earnings during such period, plus
          (to the extent deducted in determining Consolidated Net Earnings),
          (ii) all provisions for any federal, state or local income taxes made
          by the Company and its Subsidiaries during such period, plus all
          provisions for depreciation and amortization (other than amortization
          of debt discount) made by the Company and its Subsidiaries during such
          period, plus Consolidated Interest Expense during such period, plus
          other non-recurring (with the understanding that unit option expense
          shall not constitute a recurring event) non-cash losses and charges
          minus (b)(i) gains on sales of assets (excluding sales in the ordinary
          course of business) and (ii) other non-recurring (with the
          understanding that unit option credits shall not constitute a
          recurring event) non-cash gains. For purposes of any determination of
          Consolidated Operating Cash Flow pursuant to Section 6A(2)(iv)(1)(a),
          the Company may include "consolidated operating cash flow" (determined
          in a manner consistent with the definition of "Consolidated Operating
          Cash Flow" contained in this Agreement), on a pro forma basis, which
          were earned in the immediately preceding four fiscal quarter period by
          any business entity actually acquired by the Company or any of its
          Subsidiaries during such period, provided that concurrently with such
          determination, the Company shall have furnished to the holders of the
          Notes audited financial statements (if the Company is required
          pursuant to Regulation S-X to prepare audited financial statements in
          connection with such acquisition) and other financial information with
          respect to such business entity demonstrating to the reasonable
          satisfaction of the Required Holders the basis for the inclusion and
          computations of such "consolidated operating cash flow".

                    "CURRENT INDEBTEDNESS" of any Person means as of the date of
          any determination thereof (a) all Indebtedness of such Person for
          borrowed money other than Funded Indebtedness of such Person,
          including all Revolver Debt of such Person, and (b) Guaranties by such
          Person of Current Indebtedness of others.

                    "FUNDED INDEBTEDNESS" of any Person means, without
          limitation, (a) all Indebtedness of such Person for borrowed money or
          which has been incurred in connection with the acquisition of assets
          in each case having a final maturity of one or more than one year from
          the date of origin thereof (or which is renewable or extendible at the
          option of the obligor for a period or periods more than one year from
          the date of origin), including all payments in respect thereof that
          are required to be made within one year from the date of any
          determination of Funded Indebtedness, whether or not the obligation to
          make such payments shall constitute a current liability of the obligor
          under GAAP, (b) all Capitalized Rentals of such Person, and (c) all
          Guaranties by such Person of Funded Indebtedness of others; provided
          that, notwithstanding the maturity of such Indebtedness, "Funded
          Indebtedness" shall not include Revolver Debt of such Person but shall
          include any term debt having a final


                                                                               4

<PAGE>

          maturity of one or more than one year regardless of whether such term
          debt originally constituted, or was converted from, Revolver Debt.

                    "GUARANTY" means, with respect to any Person, any obligation
          (except the endorsement in the ordinary course of business of
          negotiable instruments for deposit or collection) of such Person
          guaranteeing or in effect guaranteeing any Indebtedness, dividend or
          other obligation of any other Person in any manner, whether directly
          or indirectly, including (without limitation) obligations incurred
          through an agreement, contingent or otherwise, by such Person:

                         (a) to purchase such Indebtedness or obligation or any
               property constituting security therefore;

                         (b) to advance or supply funds (i) for the purchase or
               payment of such Indebtedness or obligation, or (ii) to maintain
               any working capital or other balance sheet condition or any
               income statement condition of any other Person or otherwise to
               advance or make available funds for the purchase or payment of
               such Indebtedness or obligations;

                         (c) to lease properties or to purchase properties or
               services primarily for the purpose of assuring the owner of such
               Indebtedness or obligation of the ability of any other Person to
               make payment of the Indebtedness or obligation; or

                         (d) otherwise to assure the owner of such Indebtedness
               or obligation against loss in respect thereof.

          In any computation of Indebtedness or other liabilities of the obligor
          under any Guaranty, the Indebtedness or other obligations that are the
          subject of such Guaranty shall be assumed to be direct obligations of
          such obligor.

                    "INTEREST EXPENSE" of the Company and its Subsidiaries for
          any period means all interest (including the interest component on
          Rentals on Capitalized Leases) and all amortization of debt discount
          and expense on any particular Indebtedness (including, without
          limitation, payment-in-kind, zero coupon and other like Securities)
          for which such calculations are being made. Computations of Interest
          Expense on a pro forma basis for Indebtedness having a variable
          interest rate shall be calculated at the rate in effect on the date of
          any determination.

                    "RENTALS" means and include as of the date of any
          determination thereof all fixed payments (including as such all
          payments which the lessee is obligated to make to the lessor on
          termination of the lease or surrender of the property) payable by any
          the Company or a Subsidiary, as lessee or sublessee under a lease of
          real or personal property, but shall be exclusive of any amounts
          required to be paid by the Company or a Subsidiary (whether or not
          designated as rents or additional rents) on account of maintenance,
          repairs, insurance, taxes and similar charges. Fixed rents


                                                                               5

<PAGE>

          under any so-called "percentage leases" shall be computed solely on
          the basis of the minimum rents, if any, required to be paid by the
          lessee regardless of sales volume or gross revenues.

                    "REVOLVER DEBT" means as of the date of any determination
          thereof all Indebtedness of a Person under a revolving credit
          agreement which, by its terms, permits the re-borrowing of amounts
          re-paid under such agreement, subject to customary requirements.

                    "SECURITY" has the meaning set forth in Section 2(1) of the
          Securities Act of 1933."

     1.4 Paragraph 6C of each Shelf Agreement is amended by deleting such
paragraph 6C and replacing it with a new paragraph 6C to read as follows:

          "6C. CONSOLIDATED EBITDA RATIO. The Company will not at any time
     permit the ratio of (i) the amount of its Average Consolidated Debt at such
     time to (ii) its Consolidated EBITDA for the Testing Period most recently
     ended, to exceed 3.50 to 1.00."

     1.5 Paragraph 6D in each Shelf Agreement is amended by deleting the
reference to "$270,000,000" in clause (a) thereof and replacing it with
"$350,000,000".

     1.6 Paragraph 6 in each Shelf Agreement is amended by adding a new
Paragraph 6E after Paragraph 6D in each Shelf Agreement to read as follows:

          "6E. INTEREST COVERAGE RATIO. The Company will not suffer or permit at
     any time the Interest Coverage Ratio to be less than 3.50 to 1.00."

     1.7 Paragraph 7A of each Shelf Agreement is amended by inserting ", 5.14,
5.25" after the reference to "5.12" in subclause (xv)(1) of paragraph 7A in each
Shelf Agreement.

     1.8 The definitions of "Credit Agreement" and "Intercreditor Agreement" in
Paragraph 10B of each Shelf Agreement are amended and restated in their entirety
to read as follows:

               "CREDIT AGREEMENT" shall mean that certain Credit Agreement,
          dated as of March 14, 2006 among the Co-Issuers, Cedar Fair and Magnum
          Management Corporation, as borrowers, the financial institutions named
          therein as Banks and KeyBank National Association, as lead arranger
          and administrative agent, as amended, restated or otherwise modified
          from time to time.

               "INTERCREDITOR AGREEMENT" shall mean that certain Intercreditor
          Agreement, dated as of March 14, 2006, among the agent and the banks
          party to the Credit Agreement, the purchasers under the 2002 Note
          Purchase Agreement, the purchasers under the 2003 Note Purchase
          Agreement and the holders of the Notes, as amended, restated or
          otherwise modified from time to time.


                                                                               6

<PAGE>

     1.9 The following new definition(s) are added to Paragraph 10B of each
Shelf Agreement in alphabetical order:

               "AVERAGE CONSOLIDATED DEBT" shall mean, on any date of
          determination, the average of the aggregate amount of Consolidated
          Debt outstanding as of the last day of each of the most recently
          completed four fiscal quarters.

               "INTEREST COVERAGE RATIO" shall mean "Interest Coverage Ratio" as
          defined in the Credit Agreement as in effect on the date hereof and
          with such modifications to such definition as the Required Holder(s)
          may consent to in writing. No modification or termination of the
          Credit Agreement shall affect the continued applicability of the
          foregoing reference thereto.

               "LEVERAGE FEE" shall have the meaning provided in paragraph 5L.

     SECTION 2. CONDITIONS PRECEDENT. This letter shall become effective as of
the date first written above upon (a) the return by the Co-Issuers to Prudential
of a counterpart hereof duly executed by the Co-Issuers and the holders of the
Notes and consented to by the subsidiaries of the Company listed below and (b)
delivery of a fully executed copy of the Credit Agreement in form and substance
satisfactory to the Required Holders. The foregoing documentation should be
returned to Prudential Capital Group, Two Prudential Plaza, Suite 5600, Chicago,
Illinois 60601, Attn: Scott B. Barnett.

     SECTION 3. REPRESENTATIONS AND WARRANTIES. Each Co-Issuer represents and
warrants that: (a) each Shelf Agreement, as amended, is the legal, valid and
binding obligations of each Co-Issuer, enforceable against each Co-Issuer in
accordance with its terms, except as enforceability thereof may be limited by
applicable bankruptcy, insolvency, reorganization, moratorium or similar laws
affecting the enforcement of creditors' rights generally and by the availability
of the remedy of specific performance, (b) each representation and warranty set
forth in paragraph 8 of the Shelf Agreements is true and correct as of the date
of execution and delivery of this letter by the Co-Issuers with the same effect
as if made on such date (except to the extent such representations and
warranties expressly refer to an earlier date, in which case they were true and
correct as of such earlier date) and (c) after giving effect to this letter, no
Event of Default or Default exists on the date hereof.

     SECTION 4. REFERENCE TO AND EFFECT ON SHELF AGREEMENTS. Upon the
effectiveness of this letter, each reference to either Shelf Agreement in any
other document, instrument or agreement shall mean and be a reference to such
Shelf Agreement, as modified by this letter. Except as specifically set forth in
Section 1 hereof, each Shelf Agreement shall remain in full force and effect and
is hereby ratified and confirmed in all respects.

     SECTION 5. GOVERNING LAW. THIS LETTER SHALL BE CONSTURED AND ENFORCED IN
ACCORDANCE WITH, AND THE RIGHTS OF THE PARTIES SHALL BE GOVERNED BY, THE LAW OF
THE STATE OF ILLINOIS (EXCLUDING ANY CONFLICTS OF LAW RULES WHICH WOULD
OTHERWISE CAUSE THIS AGREEMENT TO BE CONSTRUED OR ENFORCED IN ACCORDANCE WITH,
OR


                                                                               7

<PAGE>

THE RIGHTS OF THE PARTIES TO BE GOVERNED BY, THE LAWS OF ANY OTHER
JURISDICTION).

     SECTION 6. COUNTERPARTS; SECTION TITLES. This letter may be executed in any
number of counterparts and by different parties hereto in separate counterparts,
each of which when so executed and delivered shall be deemed to be an original
and all of which when taken together shall constitute but one and the same
instrument. The section titles contained in this letter are and shall be without
substance, meaning or content of any kind whatsoever and are not a part of the
agreement between the parties hereto.

             The remainder of this page is intentionally left blank.


                                                                               8

<PAGE>

          SECTION 7. CONFIRMATION OF GUARANTEES. By its signature below, each
Subsidiary party to a Guaranty Agreement agrees and consents to the terms and
provisions of this letter and agrees that its Guaranty Agreement shall remain in
full force and effect after giving effect to this letter.

                                        Very truly yours,

                                        PRUDENTIAL INVESTMENT MANAGEMENT, INC.


                                        By:
                                            ------------------------------------
                                            Vice President


                                        THE PRUDENTIAL INSURANCE
                                        COMPANY OF AMERICA


                                        By:
                                            ------------------------------------
                                            Vice President


                                        HARTFORD LIFE INSURANCE COMPANY

                                        By: Prudential Private Placement
                                            Investors, L.P.
                                            (as Investment Advisor)

                                        By: Prudential Private Placement
                                            Investors, Inc.
                                            (as its General Partner)


                                        By:
                                            ------------------------------------
                                            Vice President


                                        MEDICA HEALTH PLAN

                                        By: Prudential Private Placement
                                            Investors, L.P.
                                            (as Investment Advisor)

                                        By: Prudential Private Placement
                                            Investors, Inc.
                                            (as its General Partner)


                                        By:
                                            ------------------------------------
                                            Vice President


                                                                               9

<PAGE>

                                        BAYSTATE INVESTMENTS, LLC

                                        By: Prudential Private Placement
                                            Investors, L.P.
                                            (as Investment Advisor)

                                        By: Prudential Private Placement
                                            Investors, Inc.
                                            (as its General Partner)


                                        By:
                                            ------------------------------------
                                            Vice President


                                        SECURITY BENEFIT LIFE INSURANCE
                                        COMPANY, INC.

                                        By: Prudential Private Placement
                                            Investors, L.P.
                                            (as Investment Advisor)

                                        By: Prudential Private Placement
                                            Investors, Inc.
                                            (as its General Partner)


                                        By:
                                            ------------------------------------
                                            Vice President


                                        ING LIFE INSURANCE AND ANNUITY COMPANY

                                        By: Prudential Private Placement
                                            Investors, L.P.
                                            (as Investment Advisor)

                                        By: Prudential Private Placement
                                            Investors, Inc.
                                            (as its General Partner)


By:
    ---------------------------------
    Vice President


                                                                              10

<PAGE>

Agreed and accepted this
14th day of March, 2006

CEDAR FAIR, L.P.

By: Cedar Fair Management Company,
    General Partner


By:
    ---------------------------------
Name: Peter J. Crage
Title: Corporate Vice President,
       Finance


KNOTT'S BERRY FARM

By: Magnum Management Corporation,
    one of its general partners


By:
    ---------------------------------
Name: Peter J. Crage
Title: Corporate Vice President,
       Finance


Consented:

CEDAR FAIR

By: Magnum Management Corporation,
    the Managing General Partner


By:
    ---------------------------------
Name: Peter J. Crage
Title: Corporate Vice President,
       Finance


MAGNUM MANAGEMENT CORPORATION


By:
    ---------------------------------
Name: Peter J. Crage
Title: Corporate Vice President,
       Finance


MICHIGAN'S ADVENTURE, INC.


By:
    ---------------------------------
Name: Peter J. Crage
Title: Corporate Vice President,
       Finance


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