By building the PIM Initiative, the European and International Delegation of France’s Conservatoire du Littoral et des Rivages Lacustres (Coastal Protection Agency) aims to use small islands as laboratories to unite actors and build ambitious environmental policies in the western Mediterranean basin. This study examines the position of these small islands as a relevant model for conservation policies and actions. It is based on data collected during a two-year immersion in the PIM Initiative and uses several methodological and analytical tools. While working on the small islands of the Mediterranean basin, the PIM Initiative uses three main techniques: building a collective, gathering environmental data, and spreading a representation of these territories to wider publics. These techniques are analyzed using the framework of the circulatory system of scientific facts (Latour, 1999). This analysis highlights three preconceptions: (i) small islands group a limited number of actors, (ii) islands attract and facilitate consensus, and (iii) actions implemented on small islands can be replicated on larger islands and the mainland. The article concludes by discussing how the PIM Initiative is poised between considering small islands as laboratories which should become models for environmental policies, or as key sensors, specific territories which highlighted some broader features.