The 48-hour hackathon “AI & the Ocean”, co-organized by the Athena Research Center and the EU projects DataGEMS (co-organizer), Code4Europe, and Co-Waters, successfully took place at the French Institute of Greece (25–27 November 2025). The opening session was led by Eleni Petra, Chair of the Organizing Committee and Project Manager of DataGEMS, who welcomed participants and introduced the goals, themes, and rules of the hackathon.