This paper contributes to the emerging field of forest pedagogies by foregrounding mangroves as critical sites for learning with more-than-human entanglements in polluted worlds. Engaging with planetary strategies of corresponding, evidencing and circulating, we approach mangroves as complex, contested and vital ecotones. We explore how mangroves invite pedagogical attention to the lived realities of toxicity, urbanisation and forms of contamination in the emergence of the Anthropocene. We conceptualise mangroves as “unruly edges” that unsettle binary distinctions between forest and estuary, fresh and saline waters and call for an estimation, historisation and analyses of interspecies entanglements. This position grounds a critical pedagogical project of “riparian struggles,” fostering mutual learning among river-zone inhabitants across planetary contexts. Through a case study in the Guanabara Bay region of Rio de Janeiro, we present filmmaking as a threefold tactic that (1) situates mangrove struggles within broader historical geographies, (2) supports community-based and student learning with contaminated ecologies and (3) circulates tactics of mangrove struggles across academic, educational and public spheres. Ultimately, we propose mangroves as more-than-human classrooms where practices of habitability with toxicity can be cultivated, unsettling paradigms of ecological purity and expanding forest imaginaries within the field of Critical Forest Studies.