MerTerre is an association specialized in wastes left. The expertise of the association has been developed around the intersection of natural and social sciences. To handle, you need to know. It is a matter of providing knowledge on the quantities, qualities and origins of marine litter in order to define reduction programs and adapted means. It is known that 80% of waste in the ocean comes from the land. It is crucial to improve their consideration of this new environmental issue in the watersheds. Indeed, the territories of local authorities involving a network of heterogeneous actors complex and not used to working together, must take hold of the problem and in particular around the sectors of waste and water. Convinced that this aspect of coordination of stakeholders is crucial to ensure the success of measures to reduce this pollution, MerTerre creates tools and programs that increase the capacity to work in the same direction and carry out concrete actions to reduce marine litter. In 2019, with the support of the Provence-Alpes-Côte d'Azur Region and the Ministry of Ecological Transition, MerTerre created the ReMed Zero Plastic platform. Developed in partnership with the Musée National D'Histoire Naturelle, ReMed gathers and federates, on the scale of the southern region, all structures wishing to contribute to the reduction of litter arriving in the Mediterranean and invites them to use homogeneous characterization and awareness-raising tools in order to optimize their clean-ups. In 2021, the national equivalent of ReMed Zero Plastic: Zero Litter is launched. With its centralized database for France, the association wishes to obtain a cartography in time and space of marine litter in order to establish reduction plans adapted to the territories.