In this thesis, I explore shifting understandings of human embodiment, society, and the environment in light of recent advances in posthumanist and neo-materialist theory, which invite us to move beyond anthropocentric frameworks and craft alternative and more ethical ways of existing on the planet alongside nonhuman entities. I look at contemporary science fiction as a site of creative imagining and appraisal for new possibilities that contest and rewrite of dominant versions of the human that rest their hegemony on the oppression of sexualised, racialised, and naturalised Others. Drawing on current, innovative perspectives from the fields of the Environmental and the Blue Humanities, this thesis focusses on aquatic worlds as a prism through which to follow the emergence of practices, embodiments, as well as kinships and affective relations that rest on and illuminate the intrinsic connectedness and interdependence between human and nonhuman bodies, therefore troubling or undoing the purported superiority of white, male, Western, heteropatriarchal anthropos. This research aims to enrich existing studies on bodies of water and more-than-human entanglements by performing, through science fiction, situated analyses of what posthumanist and neo-materialist thought means and entails from the frameworks of gender, Blackness, and indigeneity. With this, I enter in conversation with interdisciplinary studies that have critiqued the methods and findings of posthuman discourses, accusing them of perpetuating acts of appropriation and erasure of marginalised perspectives. Against the abstractedness of theoretical takes on the post-anthropocene, I rest on water and science fiction to explore how the possibility of undoing hegemonic Man is imagined and experienced by those living in the margins of his domains.