The sea level rise challenges the future of coastal areas. Although since 2012 in France, the State and local authorities have been working on the future of urbanised coastlines within the framework of the national strategy for the integrated management of the coastline, the natural coastal environments have been the great omission from these discussions. Marginal spaces whose marine and/or land boundaries are constantly being questioned by regulations and the pressures exerted by urbanization, they are also the first to be impacted in the event of marine submersion or erosion. Their marginality is also the result of the low stakes involved, in a reflection essentially centred on urban areas. Recently, however, a reverse trend has emerged and the future of these heritage areas is being questioned. As with other types of territory, the question is whether to resist or adapt. Could this adaptation involve the relocation of certain ecosystems ? This article proposes to answer these questions based on surveys conducted as part of a research project on several French nature reserves.