Exhibit 99.1 C3is Inc. C3is Inc. reports financial and operating results for the first quarter of 2025 Athens, Greece, May 15, 2025 – C3is Inc. (Nasdaq: CISS) (the "Company"), a ship-owning company providing dry bulk and tanker seaborne transportation services, announced today its unaudited financial and operating results for the first quarter ended March 31, 2025. OPERATIONAL AND FINANCIAL HIGHLIGHTS 1 • Our handysize dry bulk carriers are on time charters of short-term durations, producing steady cash flo ...