The European Marine Observation and Data Network (EMODnet) is organising the third edition of the Open Sea Lab 3.0 hackathon –OSL 3.0–, a virtual event with support from the European Commission Directorate-General for Maritime Affairs and Fisheries (DG MARE), the Flanders Marine Institute (VLIZ), the International Council for the Exploration of the Sea (ICES), the Copernicus Marine Service and Marine@UGent. Seascape Belgium as administrator of the EMODnet Secretariat is coordinating the organisation of the event. The event will take place in March 2023, kicking off with an Ideation & Team Formation warm-up, followed by a 2-day virtual hackathon on 27-28 March and a closing, Pitching & Award Event on 30 March 2023. The full agenda of the event will be disclosed soon.