amJERICO-RI: Joint European Research Infrastructure of Coastal Observatories – a system of systems strengthening the European network of coastal observatories providing a powerful and structured European Research Infrastructure (RI) dedicated to observe and monitor the complex marine coastal seas and to: (i) provide services for the delivery of high quality environmental data, (ii) access to solutions and facilities as services for researchers and users, (iii) create product prototypes for EU marine core services and users, (iv) support excellence in marine coastal research to better answer societal and policy needs. JERICO-S3 will provide a state-of-the-art, fit-for-purpose and visionary observational RI, expertise and high-quality data on European coastal and shelf seas, supporting world-class research, high-impact innovation and a window of European excellence worldwide. It will significantly enhance the current value and relevance of the JERICO-RI, through the implementation of the science and innovation strategy elaborated as part of the JERICO-NEXT project. JERICO-S3 is mainly targeting a more science integrative approach to better observe the coastal ecosystem, raising up the scientific excellence, with consideration of the regional and local ecosystems; the preliminary development of an e-infrastructure in support to scientists and users by offering access to dedicated services; progress on the design of the RI and its strategy for sustainability. Major user-driven improvements will be realised in terms of observing the complexity of coastal seas and continuous observation of the biology, access to facilities, data and services, best practices and performance indicators, innovative monitoring strategies, cooperation with other European RIs (EuroARGO, EMSO, AQUACOSM, DANUBIUS, ICOS, EMBRC, LIFEWATCH) and international scientific communities, industry and other stakeholders, and aligning strategy with COPERNICUS/CMEMS, EMODNET and GEO/GEOSS.