This contribution deals with the role of geographical information in participatory research concerning coastal zones and its potential to bridge the gap between research and coastal zone management. The study aims at modeling the interactions between human activities in a maritime basin. A methodology is proposed to describe the spatio-temporal distribution of several activities in coastal sea. An application is developed in the Bay of Brest (Brittany, France). Spatial, temporal, quantitative and qualitative data acquisition combines analysis of spatio-temporal databases and results from interviews. The heterogeneous data collected are stored in a spatio-temporal database (STDB) and used within a GIS. This Time-GIS is used as a tool to facilitate the exchange of points of view and to share knowledge. Geographic information technologies are used at several levels: data collection, GIS analysis, mapping, and simulations. The results show that the GIS-based capture data is well managed by the stakeholders who are interested in contributing to the process of gathering scientific data. The results of a participatory workshop with stakeholders show that the dynamic component of the data adds a real value for management. The possibility to use such a dynamic GIS to discuss and simulate management scenarios is tested, but it needs to be built up gradually.