This paper focuses on a case of coastal erosion, taking place on the beaches of the National park of the archipelago of la Maddalena, in Sardinia (Mediterranean Sea), in the middle of an internationally renowned touristic area. Conducting fieldwork here makes it possible to investigate the relations occurring between environmental conservation and economical development issues, in a specific context, at the intersection of socio-ecological dynamics crossing multiple scales and levels. Thanks to ethnographical observation, experiences of environmental conservation can be analyzed as the outcome of adaptation processes, either to paradigms coming from the global arena, either to local agendas. We are interrogating viewpoints and priorities expressed by a plurality of actors, involved in coastal spaces regulation. Those persons are also deeply embedded in socio-historical contexts, that we must consider in order to grasp present complexities. Proposing to look attentively at different knowledges and environments at stake, some anthropological and sociological perspectives help analyzing environmental controversies, without trying to drive them to a univocal axiological frame. Finally, I invite to acknowledge this case as an opportunity to think at political dimensions of environmental uncertainties, at the interface between socio-ecological phenomena, vaguenesses coming from scientific knowledges, policymaking, and politico-economic and historical issues.