Amendment No. 3 to Schedule 13D for C3IS Inc.

This Amendment No. 3 to Schedule 13D, filed on October 1, 2025, updates the ownership details of the common stock of C3IS Inc. by the Reporting Persons: Flawless Management Inc., Arethusa Properties LTD, and Harry N. Vafias. The amendment reflects changes in the percentage of shares beneficially owned by the Reporting Persons due to dilution based on the revised total number of outstanding shares, as reported in the Issuer's Form 6-K filed on September 29, 2025. The Reporting Persons acquired the securities for investment purposes and may acquire additional securities, retain, or sell shares based on various factors, including the Issuer's business, financial condition, and market conditions. Harry N. Vafias, the Non-Executive Chairman of the Issuer, regularly engages in discussions with management and the board, which may include considerations of extraordinary corporate transactions. The amendment also includes a Joint Filing Agreement dated October 1, 2025, among the Reporting Persons.