The European project MERCES Marine Ecosystem Restoration in Changing European Seas http://www.merces-project. eu/ - funded under the Horizon 2020 action, is the first European project that focuses entirely on the restoration of marine ecosystems by focusing on various types of degraded habitats, and the biodiversity, functions, goods and services they provide. The project involves 28 actors from 16 countries and more than 300 scientists from a wide range of disciplines. MERCES will contribute to the implementation of the European Restoration Agenda through Pilot Experimental Actions and several surveys/reviews. The first Work Package, focuses on the review of information on the existence of available maps, the inventory of key and degraded marine ecosystems in the European seas, their level of degradation, the main anthropogenic pressures and the possibilities for restoration. Moreover, a review of the available information for 6 European marine habitats of key importance was conducted. Preliminary outcomes of WP1 suggest the need for enhancement and integration of available knowledge, on interactive, multi-purpose map resources, to provide a sound basis for the design of marine restoration actions in Europe.