Indigenous peoples dispute the material and symbolic control of territory and nature in confronting the “coloniality of nature,” proposing respect for knowledge and environmental relations that modernity-coloniality-capitalism have denied. In these disputes, they ways that nature, energy and water are used and their meaning are at the center of the debate. This work presents a decade of participatory action research with Mapuche organizations, with which strategies against the installation of extractive projects have been deployed. In these experiences, we highlight the use of the concept of ixofillmongen as a category of Mapuche knowledge that proposes a relational ontological approach to other life forms that are part of nature. Here we present its use as part of a Mapuche strategy to decolonize nature implemented against the installation of hydroelectric plants. Based on this work, we developed a participatory action research methodology that other indigenous communities can replicate for the design of collective research experiences and the creation of alternative territorial strategies. The research results show that it is possible to build strategies for the recovery of water based on native peoples’ territorial and natural knowledge and get them to dialogue with critical and decolonial geography.