The coastline, as well as being the interface between land and sea, is also where interactions occur and conflicts may arise between local and global dynamics. In cases such as these, how can an area-based general interest be constructed that combines both local and superregional interests? We conducted a comparative analysis of eight case studies addressing either the creation of protected areas at the interface between local dynamics and national and international requirements, or projects justified by the fight against climate change that have nevertheless met with local opposition (e.g. offshore wind farms or inland waterways for multimodal transport). The analysis reveals recurrences, with five mechanisms used to construct an area-based public interest and the project’s acceptance: the generally tacit prioritising of stakeholders, issues and/or scales ; creating and making use of projects’ adjustment variables ; transactions between stakeholders ; spatial exit, with certain activities transferred out of the area ; and the construction of new organised proximities. These mechanisms – which are complementary rather than alternative – make up the “HAPTE” grid (Hiérarchisation, Ajustement, Proximités, Transaction, Exit or Prioritisation, Adjustment, Proximities, Transaction, Exit). However, some of the mechanisms are skewed, making the agreement fragile. This results in three archetype processes with three possible outcomes: a dynamic area-based compromise, a skewed and fragile compromise or stonewalling and avoidance strategies. Based on our analysis, we propose a grid to evaluate the mechanisms mobilised to construct an agreement, enabling the quality of its underlying area-based general interest to be assessed.