CS-MACH1 aims to overcome existing barriers to citizen science empowerment, such as accessibility, recognition, trust, and sharing of marine citizen science data, by establishing and managing a Marine Citizen Science Data Network (MCSDN) of and for citizen science initiatives, community representatives, cost-efficient technology developers, data management experts, and scientists. To support the production of FAIR data and the integration of citizen science data into EU platforms like EMODnet, CS-MACH1 will produce standards, best practices for deployment and data management, observation protocols for using cost-effective devices, and training materials to guide citizen science coordinators in managing their data flow. The value chain of the MCSDN will be demonstrated by addressing local challenges in real-world use-cases, co-designed with end-users and used for beta testing innovations and the proposed data flow. The scientific and societal impacts of the MCSDN will be demonstrated through the validation of Digital Twin Ocean models, policy workshops, and extended dissemination of results to attract and empower a larger number of marine citizen science actors and citizen scientists. A roadmap outlining strategies for a continuous workflow will ensure the sustainability of the project's outcomes and the legacy of the network.