Oceanhawk Acquisition Corp.

As filed with the U.S. Securities and Exchange Commission on March 20, 2026.

Registration No. 333-

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORMS-1

REGISTRATION STATEMENT

UNDER

THE SECURITIES ACT OF 1933

(Exact Name of Registrant as Specified in its Charter)

515 Madison Avenue, 8 th Floor

New York, NY 10022

United States of America

Telephone: (212) 931-1898

(Address, including Zip Code, and Telephone Number, including Area Code, of Registrant’s Principal Executive Offices)

Ernest Miller

Chief Executive Officer

515 Madison Avenue, 8 th Floor

New York, NY 10022

United States of America

Telephone: (212)931-1898

(Name, Address, including Zip Code, and Telephone Number, including Area Code, of Agent for Service)

Copies to:

Approximate date of commencement of proposed sale to the public: As soon as practicable after the effective date of this registration statement.

If any of the securities being registered on this Form are to be offered on a delayed or continuous basis pursuant to Rule 415 under the Securities Act of 1933, check the following box.☐

If this Form is filed to register additional securities for an offering pursuant to Rule 462(b) under the Securities Act, check the following box and list the Securities Act registration statement number of the earlier effective registration statement for the same offering.☐

If this Form is a post-effective amendment filed pursuant to Rule 462(c) under the Securities Act, check the following box and list the Securities Act registration statement number of the earlier effective registration statement for the same offering.☐

If this Form is a post-effective amendment filed pursuant to Rule 462(d) under the Securities Act, check the following box and list the Securities Act registration statement number of the earlier effective registration statement for the same offering.☐

Indicate by check mark whether the registrant is a large accelerated filer, an accelerated filer, a non-accelerated filer, a smaller reporting company, or an emerging growth company. See the definitions of “large accelerated filer,” “accelerated filer,” “smaller reporting company,” and “emerging growth company” in Rule 12b-2 of the Exchange Act.

If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 7(a)(2)(B) of the Securities Act.☐

The registrant hereby amends this registration statement on such date or dates as may be necessary to delay its effective date until the registrant shall file a further amendment which specifically states that this registration statement shall thereafter become effective in accordance with Section 8(a) of the Securities Act of 1933, as amended, or until the registration statement shall become effective on such date as the Securities and Exchange Commission, acting pursuant to said Section 8(a), may determine.

The information contained in this preliminary prospectus is not complete and may be changed. No securities may be sold until the registration statement filed with the Securities and Exchange Commission is effective. This preliminary prospectus is not an offer to sell these securities, and it is not soliciting an offer to buy these securities, in any jurisdiction where the offer or sale is not permitted.

SUBJECT TO COMPLETION, DATED MARCH 20, 2026

PRELIMINARY PROSPECTUS

$200,000,000

20,000,000 Units

Oceanhawk Acquisition Corp. is a blank check company, incorporated as a Cayman Islands exempted company for the purpose of effecting a merger, share exchange, asset acquisition, share purchase, recapitalization, reorganization or similar business combination with one or more businesses, which we refer to throughout this prospectus as our initial business combination. We have not selected any business combination target, and we have not, nor has anyone on our behalf, initiated any substantive discussions, directly or indirectly, with any business combination target. While we may pursue an initial business combination target in any industry or geographic location, we intend to focus our search on high potential businesses based in the United States.

We are an “emerging growth company” and “smaller reporting company” under applicable federal securities laws and will be subject to reduced public company reporting requirements. Investing in our securities involves risks. See “Risk Factors” beginning on page 39. Investors will not be entitled to protections normally afforded to investors in Rule 419 blank check offerings.

(1) Includes (i) $0.15 per unit, or $3,000,000 in the aggregate (or $3,450,000 in the aggregate if the over-allotment option is exercised in full), payable to the underwriters upon the closing of this offering, and (ii) $0.35 per unit, or $7,000,000 in the aggregate (or $8,050,000 in the aggregate if the over-allotment option is exercised in full), payable to the underwriters for deferred underwriting commissions to be placed in a trust account located in the United States, as described herein. Does not include certain fees and expenses payable to the underwriters in connection with this offering. See “Underwriting” for a description of underwriting compensation payable to the underwriters.

Of the proceeds we receive from this offering and the sale of the private placement units described in this prospectus, $200.0 million or $230.0 million if the underwriters’ over-allotment option is exercised in full ($10.00 per unit), will be deposited into a segregated trust account located in the United States with Odyssey Transfer & Trust Company acting as trustee. Except with respect to interest earned on the funds held in the trust account that may be released to us to pay our taxes, which shall exclude any excise tax or any other similar fees or taxes that may be levied on us pursuant to any current, pending or future rules or laws, including without limitation, the Inflation Reduction Act of 2022, for any redemptions or repurchases by us (“permitted withdrawals”), if any, the funds held in the trust account will not be released from the trust account until the earliest to occur of: (1) our completion of an initial business combination; (2) the redemption of any public shares properly submitted in connection with a shareholder vote to amend our amended and restated memorandum and articles of association (A) to modify the substance or timing of our obligation to allow redemption in connection with our initial business combination or to redeem 100% of our public shares if we do not complete our initial business combination within 24 months from the closing of this offering or (B) with respect to any other provision relating to shareholders’ rights or pre-initial business combination activity; and (3) the redemption of our public shares if we have not completed an initial business combination within 24 months, from the closing of this offering, subject to applicable law. If we are unable to complete an initial business combination within the 24-month period, we may seek an amendment to our amended and restated memorandum and articles of association to extend the period of time we have to complete an initial business combination beyond 24 months. Our amended and restated memorandum and articles of association will require at least a special resolution of our shareholders as a matter of Cayman Islands law, meaning that such an amendment be approved by at least two-thirds of our ordinary shares who, being entitled to do so, attend and vote (either in person or by proxy) at a general meeting of the company. If we seek shareholder approval to extend beyond the 24-month period in which to complete an initial business combination to a later date, we will offer our public shareholders the right to have their public

ordinary shares redeemed for a pro rata share of the aggregate amount then on deposit in the trust account, including interest (less permitted withdrawals and up to $100,000 of interest to pay dissolution expenses), as described in greater detail in this prospectus.

The proceeds deposited in the trust account could become subject to the claims of our creditors, if any, which could have priority over the claims of our public shareholders.

We are not prohibited from paying any fees (including advisory fees), reimbursements or cash payments to our sponsor, officers or directors, or our or their affiliates, for services rendered to us prior to or in connection with the completion of our initial business combination. We will pay an affiliate of Oceanhawk Acquisition I Sponsor LLC, a Delaware limited liability company (which we refer to throughout this prospectus as “Oceanhawk Sponsor”) a total of $10,000 per month for office space, administrative and support services. Prior to the closing of this offering, Oceanhawk Sponsor has agreed to loan us up to $300,000 to be used for a portion of the expenses of this offering. These loans are non-interest bearing, unsecured and are due at the earlier of December 31, 2027 or the closing of this offering. The loan will be repaid upon the closing of this offering out of the $725,000 of offering proceeds that has been allocated to the payment of offering expenses. Although not currently contemplated, we may pay customary fees for financial advisory services and pay reimbursements for any out-of-pocket expenses related to identifying, investigating and completing an initial business combination. Additionally, up to $1,500,000 of any loans from our sponsor, members of our management team or any of their affiliates or other third parties, although they are under no obligation to loan funds, may be convertible into units, at a price of $10.00 per unit at the option of the lender. The units and the underlying securities would be identical to the private placement units and the underlying securities of such private placement units issued to Oceanhawk Sponsor. The additional issuance of securities that may occur as a result of the conversion of such loans into units may result in a material dilution of the equity interests of public shareholders. The terms of such loans, if any, have not been determined and no written agreements exist with respect to such loans. Furthermore, other compensation to be paid and securities issued to Oceanhawk Sponsor and any affiliates may result in a material dilution of the equity interests of public shareholders. No other compensation to be paid and securities issued to Oceanhawk Sponsor has been determined and no written agreement exists with respect to any additional compensation or securities. See the sections titled “The Offering — Anticipated expenses and funding sources”, “The Offering — Limited payment to insiders”, “Use of Proceeds”, “Management’s Discussion and Analysis of Financial Condition and Results of Operations — Liquidity and Capital Resources”, “Risk Factors — Our rights and founder shares may have an adverse effect on the market price of our Class A ordinary shares and make it more difficult to effectuate our initial business combination,” “Management’s Discussion and Analysis of Financial Condition and Results of Operations — Related Party Transactions”, “Certain Relationships and Related Party Transactions”, “Description of Securities — Registration Rights,” “Description of Securities — Private Placement Units.”

Members of our management team and our board of directors will directly or indirectly own founder shares and/or private placement units following this offering and, accordingly, may have a conflict of interest in determining whether a particular target business is an appropriate business with which to effectuate our initial business combination. See “Summary — Additional Disclosure,” “The Offering — Conflicts of interest,” “Risk Factors — Risks Relating to Oceanhawk Sponsor and Management Team — Our directors and officers will allocate their time to other businesses thereby causing conflicts of interest in their determination as to how much time to devote to our affairs. This conflict of interest could have a negative impact on our ability to complete our initial business combination,” “Risk Factors — Risks Relating to Oceanhawk Sponsor and Management Team — Our key personnel may negotiate employment or consulting agreements with a target business in connection with a particular business combination.” These agreements may provide for them to receive compensation following our initial business combination and as a result, may cause them to have conflicts of interest in determining whether a particular business combination is the most advantageous,” “Risk Factors — Risks Relating to Oceanhawk Sponsor and Management Team — Certain of our directors and officers are now, and all of them may in the future become, affiliated with entities engaged in business activities similar to those intended to be conducted by us and, accordingly, may have conflicts of interest in determining to which entity a particular business opportunity should be presented,” “Risk Factors — Risks Relating to Oceanhawk Sponsor and Management Team — Our directors, officers, security holders and their respective affiliates may have competitive pecuniary interests that conflict with our interests,” “Risk Factors — Risks Relating to Oceanhawk Sponsor and Management Team — We may engage in a business combination with one or more target businesses that have relationships with entities that may be affiliated with Oceanhawk Sponsor, our directors or officers which may raise potential conflicts of interest,” “Management — Conflicts of Interest,” “Certain Relationships and Related Party Transactions,” and “Business — Additional Disclosures.”

This is an initial public offering of our securities. Each unit has an offering price of $10.00 and consists of one Class A ordinary share and one-seventh of one whole right to receive one Class A ordinary share upon the consummation of an initial business combination. No fractional rights will be issued upon separation of the units and only whole rights will trade, so unless you purchase at least 7 units, you will not be able to receive or trade a whole right. We have also granted the underwriters a 45-day option to purchase up to an additional 3,000,000 units to cover over-allotments, if any.

We will provide our public shareholders with the opportunity to redeem, regardless of whether they abstain, vote for, or against, our initial business combination, all or a portion of their Class A ordinary shares upon the completion of our initial business combination at a per-share price, payable in cash, equal to the aggregate amount then on deposit in the trust account described below calculated as of two business days prior to the completion of our initial business combination, including interest earned on the funds held in the trust account (net of permitted withdrawals), divided by the number of then issued and outstanding Class A ordinary shares that were sold as part of the units in this offering, which we refer to collectively as our public shares, subject to the limitation that no redemptions will take place if all of the redemptions would cause our net tangible assets to be less than $5,000,001 and any limitations (including, but not limited, to cash requirements) agreed to in connection with the negotiation of terms of a proposed business combination. Additionally, if we seek shareholder approval of our initial business combination and we do not conduct redemptions in connection with our initial business combination pursuant to the tender offer rules, our amended and restated memorandum and articles of association provide that a public shareholder, together with any affiliate of such shareholder or any other person with whom such shareholder is acting in concert or as a “group” (as defined under Section 13 of the Exchange Act), will be restricted from redeeming its shares with respect to more than an aggregate of 15% of the shares sold in this offering, without our prior consent. Except for permitted withdrawals, the proceeds placed in the trust account and the interest earned thereon shall not be used to pay for possible excise tax or any other fees or taxes that may be levied on the Company pursuant to any current, pending or future rules or laws, including without limitation any excise tax due under the Inflation Reduction Act of 2022 on any redemptions or stock buybacks by the Company. If we have not completed our initial business combination within 24 months from the closing of this offering, we will redeem 100% of the public shares at a per-share price, payable in cash, equal to the aggregate amount then on deposit in the trust account, including interest (less permitted withdrawals and up to $100,000 of interest to pay dissolution expenses), divided by the number of then issued and outstanding public shares, subject to applicable law and as further described herein.

Prior to or in connection with the completion of our initial business combination, holders of the Class B ordinary shares will have the right to appoint all of our directors and may remove members of the board of directors for any reason. On any other matter submitted to a vote of our shareholders, holders of the Class B ordinary shares and holders of the Class A ordinary shares will vote together as a single class, except as required by law.

On November 21, 2025, our sponsor, Oceanhawk Sponsor, paid $25,000 in exchange for 5,750,000 Class B ordinary shares, which we refer to as founder shares. Up to 750,000 founder shares are subject to forfeiture by Oceanhawk Sponsor depending on the extent to which the underwriters’ over-allotment option is exercised. If none of the founder shares are forfeited, the resulting purchase price would be approximately $0.004 per share. Prior to the initial investment in the Company of $25,000 by Oceanhawk Sponsor, the Company had no assets, tangible or intangible. The number of founder shares issued was determined based on the expectation that the founder shares would represent 20% of the outstanding shares after this offering (excluding any shares underlying any units our initial shareholders may purchase in this offering and the ordinary shares underlying the private placement units). If we increase or decrease the size of the offering pursuant to Rule 462(b) under the Securities Act, we will effect a capitalization or share surrender or redemption or other appropriate mechanism, as applicable, immediately prior to the consummation of the offering in such amount as to maintain the ownership of our initial shareholders prior to this offering at 20% of our issued and outstanding ordinary shares (excluding any shares underlying any units our initial shareholders may purchase in this offering and the ordinary shares underlying the private placement units) upon the consummation of this offering.

The Class B ordinary shares will automatically convert into Class A ordinary shares at the time of our initial business combination, or earlier at the option of the holder, on a one-for-one basis, subject to adjustment as provided herein. Prior to or in connection with the completion of our initial business combination, holders of the Class B ordinary shares will have the right to appoint all of our directors and may remove members of the board of directors for any reason. On any other matter submitted to a vote of our shareholders, holders of the Class B ordinary shares

and holders of the Class A ordinary shares will vote together as a single class, except as required by law. The Class A ordinary shares issuable in connection with the conversion of the Class B ordinary shares may result in material dilution to our public shareholders due to the anti-dilution rights of our Class B ordinary shares that may result in an issuance of Class A ordinary shares on a greater than one-to-one basis upon conversion. The founder shares and private placement units will be worthless if we do not complete an initial business combination

Oceanhawk Sponsor has agreed to purchase 300,000 private placement units, at a price of $10.00 per unit (or 345,000 private placement units if the underwriters exercise their over-allotment option in full), in a private placement to occur concurrently with the closing of this offering. Each private placement unit will be identical to the units sold in this offering, except as described in this prospectus. We refer to these units as the private placement units throughout this prospectus. institutional investors (none of which are affiliated with any member of our management, Oceanhawk Sponsor or any other investor) and individual investors, which we refer to as the “sponsor members” throughout this prospectus, have expressed an interest to purchase, indirectly through the purchase of non-managing interest in Oceanhawk Sponsor, an aggregate of or of the 300,000 or 345,000 private placement units, respectively, being purchased by Oceanhawk Sponsor, at a price of $10.00 per unit ($ or $ out of the $3,000,000 or $3,450,000 in the aggregate), in a private placement that will close simultaneously with the closing of this offering. The Benchmark Company, LLC has agreed to purchase 200,000 private placement units (or 230,000 private placement units if the underwriters’ over-allotment option is exercised in full), at a price of $10.00 per unit, or $2,000,000 (or $2,300,000 if the underwriters’ over-allotment option is exercised in full), in a private placement that will close simultaneously with the closing of this offering. Subject to each sponsor member purchasing, through Oceanhawk Sponsor, the private placement units allocated to it in connection with the closing of this offering, Oceanhawk Sponsor will issue membership interests at a nominal purchase price to such sponsor members reflecting interests in an aggregate of Class B ordinary shares held by Oceanhawk Sponsor. None of the non-managing sponsor members shall have more than 9.9% interest in Oceanhawk Sponsor.

Because our sponsor acquired the founder shares at a nominal price, our public shareholders will incur an immediate and substantial dilution upon the closing of this offering. The sponsor members will share in any appreciation of the founder shares through their membership interests in the sponsor if we successfully complete a business combination. Accordingly, sponsor members interests in the founder shares owned by them indirectly through their membership interests in the sponsor may provide them with an incentive to vote any public shares they own in favor of a business combination, and make a substantial profit on such interests, even if the business combination is with a target that ultimately declines in value and is not profitable for other public shareholders. Further, the issuance of additional ordinary or preference shares may significantly dilute the equity interest of public shareholders. See the sections titled “Risk Factors — Risks Relating to Oceanhawk Sponsor and Management Team — Our initial shareholders paid an aggregate of $25,000 to cover certain of our offering costs in exchange for 5,750,000 founder shares, or approximately $0.004 per founder share and, accordingly, you will experience immediate and substantial dilution from the purchase of our Class A ordinary shares” and “Risk Factors — Risks Relating to Our Securities — The nominal purchase price paid by our sponsor for the founder shares may result in significant dilution to the implied value of your public shares upon the consummation of our initial business combination, and our sponsor is likely to make a substantial profit on its investment in us in the event we consummate an initial business combination, even if the business combination causes the trading price of our ordinary shares to materially decline.”

The following table illustrates the difference between the public offering price per unit and our NTBV per share, as adjusted to give effect to this offering and assuming redemption of our public shares at varying levels and the full exercise and no exercise of the over-allotment option. See the sections titled “Prospectus Summary — Dilution,” “The Offering — Founder shares conversion and anti-dilution rights,” “Risk Factors — Risks Relating to Oceanhawk Sponsor and Management Team — Our initial shareholders paid an aggregate of $25,000 to cover certain of our offering costs in exchange for 5,750,000 founder shares, or approximately $0.004 per founder share and, accordingly, you will experience immediate and substantial dilution from the purchase of our Class A ordinary shares,” “Risk Factors — Risks Relating to Our Securities — The nominal purchase price paid by our sponsor for the founder shares may result in significant dilution to the implied value of your public shares upon the consummation of our initial business combination, and our sponsor is likely to make a substantial profit on its investment in us in the event we consummate an initial business combination, even if the business

combination causes the trading price of our ordinary shares to materially decline,” “Risk Factors — Risks Relating to Our Securities — We may issue additional Class A ordinary shares or preference shares to complete our initial business combination or under an employee incentive plan after completion of our initial business combination.”

Prior to this offering, there has been no public market for our units, Class A ordinary shares or public rights. We have applied to list our units on The Nasdaq Stock Market (“Nasdaq”) under the symbol “OHACU” on or promptly after the date of this prospectus. We cannot guarantee that our securities will be approved for listing on Nasdaq. The Class A ordinary shares and public rights constituting the units will begin separate trading on the 52 nd day following the date of this prospectus (or, if such date is not a business day, the following business day) or earlier, with the consent of The Benchmark Company, LLC, subject to our filing a Current Report on Form 8-K with the Securities and Exchange Commission (the “SEC”) containing an audited balance sheet of the company reflecting our receipt of the gross proceeds of this offering and issuing a press release announcing when such separate trading will begin. Once the securities constituting the units begin separate trading, we expect that the Class A ordinary shares and public rights will be listed on Nasdaq under the symbols “OHAC” and “OHACR,” respectively.

The underwriters are offering the units for sale on a firm commitment basis. Delivery of the units will be made on or about 2026.

We are responsible for the information contained in this prospectus. We have not authorized anyone to provide any information or to make any representations other than those contained in this prospectus. We and the underwriters take no responsibility for, and can provide no assurance as to the reliability of, any other information that others may give you. This prospectus is an offer to sell only the units offered hereby, but only under circumstances and in jurisdictions where it is lawful to do so. The information contained in this prospectus is current only as of its date.

Neither the SEC nor any state securities commission has approved or disapproved of these securities or determined if this prospectus is truthful or complete. Any representation to the contrary is a criminal offense.

No invitation, whether directly or indirectly, may be made to the public in the Cayman Islands to subscribe for our securities.

Sole Book-Running Manager

Benchmark

a StoneX Company

The date of this prospectus is , 2026