The intensity and magnitude of change that characterize coastal areas now demand the implementation of collective processes and tools to enhance coastal zone knowledge and management. Our hypothesis is that Coastal Spatial Data Infrastructures (CSDI) can contribute to Integrated Coastal Zone Management (ICZM) through a combination of technologies, policies and institutional arrangements to improve data access and sharing processes. However, their real contribution depends on the answers they provide to public bodies. This article presents the first results of a project whose goal is to implement an SDI dedicated to marine and coastal areas as a sub-set of a regional (subnational) SDI (Brittany Region, France). Based on interviews with key public ICZM stakeholders, this study examines the implementation of a data repository and a specific geoportal, and proposes a set of indicators for monitoring coastal areas.