Marine conservation has become one of the main factors in the transformation of oceans, reshaping the relations of power which define the future of such zones, with the participation of diverse agents in decision-making. This paper analyzes the creation of Marine Protected Areas in the Corcovado Gulf in Chilean Northern Patagonia. It reveals that these Marine Protected Areas are i) a response to a controversial process of territorial transformation, aggravated by the expansion of the salmon industry and calls for the conservation of biodiversity; ii) the emergence of a conservationist assemblage, based on the idea of collective efforts, and its involvement in a multi-agent network of governance.