The continued campaign of violence by extractivists against multibeing relations, embodied beings, and ecological living is bewildering. Coded by mastery, and as a carrier of its values, international laws of the sea facilitate these campaigns by legitimating ecological abuse. As such, responding to the ocean's declining conditions with more laws and regulations alone misses how underlying cultural values contribute to the production of ecological harm. This article considers how the imaginary of mastery underpinning dominant ocean governance regimes enables the production and distribution of vulnerability. Thinking with the ocean reveals how anthropogenic harms manifest and proliferate both materially and through the discursive networks of ocean governance. Though material vulnerability is a condition that brings us into being interconnectedly with other worlds, it also (unevenly) implicates us in ocean harm. This article draws on feminist posthumanist, legal, and marine scientific work to examine these issues in the context of an emerging concept of ocean justice, in which the conditions for cohabiting well with the seas might be imagined and activated.