A better understanding of recreational boating and water-based leisure activities is essential to plan and manage infrastructures, protected areas, and to understand the potential environmental impacts and conflicts. However, managers and scientific communities mention the lack of information related to «human dimension» of the marine environnment (St Martin, All-Harber, 2008). The methods of qualitative, quantitative and spatio-temporal data aquisition on marine and open sea areas often remain insufficiently available or fragmented. Project funded by This research further contributes to present and evaluate the main methods implemented for the spatial and dynamic analysis of water-based frequentation in marine protected areas in France. Low «fingerprint» on sea Mobile practices The comprehensive study of recreational boating and water-based activities requires various data: quantifying boats and flows (number of boats, type, size, age), monitoring their temporal course (periods of high frequentation), spatializing frequentation (sea lanes and preferential destinations) and characterizing practices (categories of users, motivations, perception of the activity and its environment).