Based on two projects between Telecom Bretagne and the Marine Hydrographic and Oceanographic Service (SHOM) in France, this contribution is linked to integrating multi-criteria decision aiding (MCDA) and geographical information systems (GIS) with the aim of evaluating and proposing solutions to the problem of planning activities at sea. The first project focused on the problem of ordinal evaluation of sea areas within the French jurisdiction with respect to the need of the SHOM to perform hydrographic surveys and the development of a software prototype (MODEL) for supporting it. The second project, currently in its first stages, will build upon the first by considering any planning activity at sea. This project will integrate the entire decision aiding process and aid in collaboratively situating and structuring the problem as well as validating the recommendations from which the decision-makers will choose the final one.