UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

Form 8-K

Current Report

Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934

March 23, 2026

Date of Report (Date of earliest event reported)

Blue Water Acquisition Corp. IV

(Exact Name of Registrant as Specified in its Charter)

Registrant’s telephone number, including area code: (203) 489-2110

N/A

(Former name or former address, if changed since last report)

Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligation of the registrant under any of the following provisions:

Securities registered pursuant to Section 12(b) of the Act:

Indicate by check mark whether the registrant is an emerging growth company as defined in Rule 405 of the Securities Act of 1933 (17 CFR §230.405) or Rule 12b-2 of the Securities Exchange Act of 1934 (17 CFR §240.12b-2).

Emerging growth company ☒

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 13(a) of the Exchange Act. ☐

Item 8.01. Other Events.

As previously disclosed, on March 23, 2026 Blue Water Acquisition Corp. IV (the “Company”) consummated its initial public offering (“IPO”), which consisted of 13,000,000 units (the “Units”), including 500,000 Units issued pursuant to the partial exercise by the underwriters of their over-allotment option. Each Unit consists of one Class A ordinary share, $0.0001 par value (“Class A Ordinary Share”) and one-half of one redeemable warrant of the Company, with each whole warrant entitling the holder thereof to purchase one Class A Ordinary Share for $11.50 per share (subject to adjustment). The Units were sold at an offering price of $10.00 per Unit, generating gross proceeds of $130,000,000.

Simultaneously with the closing of the IPO, the Company consummated a private placement (the “Private Placement”) of an aggregate of 425,000 units (the “Private Units”) to the Sponsor and BTIG, at a price of $10.00 per Private Unit, generating total proceeds of $4,250,000. Each Private Unit consists of one Class A Ordinary Share and one-half of one redeemable warrant, with each whole warrant entitling the holder thereof to purchase one Class A Ordinary Share for $11.50 per share (subject to adjustment). Of those 425,000 Private Units, the Sponsor purchased 275,000 Private Units and BTIG purchased 150,000 Private Units.

As of March 23, 2026, a total of $130,000,000 of the net proceeds from the IPO and the Private Placement, which amount included $4,550,000 in deferred underwriting commissions, was deposited in a trust account established for the benefit of the Company’s public shareholders. An audited balance sheet as of March 23, 2026, reflecting receipt of the proceeds upon consummation of the IPO and the Private Placement, is included as Exhibit 99.1 to this Current Report on Form 8-K.

Item 9.01 Financial Statements and Exhibits.

(d) Exhibits

SIGNATURES

Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned hereunto duly authorized.

Dated: March 27, 2026