The first part proposes an analytical Framework for the tourism enhancement of the heritage, which deals with the complexity of the economic décisions relating to this aim, highlighting various types of possible and actual economic initiatives and their various meanings. Our approach draws on the economics of conventions in order to understand the various synergies possible between the heritage and tourism dynamics within a given territory. The second part présents an analysis of the tensions between the various possible trajectories for the specific case of the estuary islands which are the subjects of natural heritage policies, while representing an important site of cultural heritage.