With COSEA you can observe your marine environment, document coastal habitats or species, do activities, and report on pollution, infrastructure, and the blue economy. COSEA is a collaborative, participatory, and community-driven project. With your contributions on the map and your activity in the app, you help scientists better understand the impacts and drivers of marine factors to protect and foster a healthy relationship between humans and our seas. As an open, participatory, and community-driven project, COSEA invites actors, stakeholders, environment groups, associations, youth projects, and others to co-use the COSEA App for observations, data collection, and community-building. In the COSEA App, participants can add photos and data, so-called spots, on the map. By submitting their observations and documentation, they can build up an environment notebook in ther user profile and map area. It is also possible to interact, comment, and exchange with others in the user community, or simply respond to the contribution of a friend in the app with a heart or like. During the course of the project, the SPOTTERON Citizen Science App Platform will be building innovative tools for users, enabling independent and self-governed usage of COSEA for marine and coastal activities. The common goal is to extend a deep care for seas and their resilience in changing times and provide a platform for participants to learn more about marine protection, social impacts and sustainable use of natural resources.