Given the transboundary nature of the environment in Belgian marine waters, a regional approach at the North Sea basin level is of great importance in assessing environmental status. Since the end of the 1970s, Belgium has already started measurements in regional cooperation, within the framework of the regional sea convention OSPAR. The monitoring of contaminants is an example of these efforts. Recommendations at regional level are adopted as far as possible and further developed where they do not yet exist through participation in the relevant OSPAR working groups. Measurement results from several programmes are also transmitted for archiving in central databases (e.g.ICES databases DATRAS and DOME, OSPAR noise register, ... ). Belgium also took an active part in regional projects to promote further harmonisation (e.g. JMP Eunosat for eutrophication) or to start a new monitoring (e.g. JOMOPANS for ambient noise). Consultations also take place at European level, e.g. on seabed integrity (TG Seabed). More details on international cooperation are given in the monitoring programmes in annex.