Large volumes of marine data – much of it collected through observing systems and research projects and made publicly available for reuse by anybody through specialised repositories – are required for science, ocean economic activity and effective management of marine space. This report summarises the results of an OECD survey of the users of Flanders-based public marine data repositories and details how societal value is generated through their data reuses. Responses to the OECD survey reveal how Flanders’ repositories enable the reuse of marine data across a range of sectors, contribute to improved decision making, and generate benefits for wider society. Stylised value chains of public marine data are constructed and visualised from the responses, revealing information that is otherwise not collected by repositories so that they can keep access to the data as open as possible. This work is part of the OECD Value Chains of Public Marine Data project and relates to broader efforts to improve understanding of the economics of open data.