This activity is working on the development of as best as possible transboundary coherent SEA using a coherent approach and assumptions for the southern Baltic as test case for methodologies and guidance developed previously (in projects as well as in national and international fora). We are focussing on a test case area, involving as many cross-border partners/sites as possible. Based on comparing existing SEAs, analysing their similarities and differences and also checking the EBA requirements in the test case area, the progress will lead to recommendations on the integration of EBA for the national SEAs.