This article aims to describe and analyse the emergence and constitution of the public in the coastal town of San Blas, Nayarit, Mexico. Based on Rancière's notion of politics, Dewey's concept of the public, and relational approaches to ontology, we draw on ethnographic, archival and interview research to follow the tracks of human and non-human actors laying competing claims on a site considered to have different characteristics within different ontologies. We show how the worlds of progress that potentially link the site to real estate profits, tourism and fisheries development enter into conflict with those of Wixaritari and Nayéeri Indigenous peoples defending an alliance between nature and spirituality. Enacted in and through the same as their opponents' materiality, Indigenous renderings of the conflict work as a pebble in the shoe for traditional politics. In particular, we focus on the way in which the site -and its entities-becomes public and political as it gradually surrounds itself with an ontologically heterogeneous audience, and how this is dealt with in practice. We argue that, as an effect, the notion of ‘the political’ changes to encompass not only a politics of who, but also a politics of what –of life itself. We conclude that the public emerges from, and is constituted by, ontological difference.