Festering ocean conflict thwarts efforts to realize the Agenda 2030 Sustainable Development Goals. This paper explores transformations of ocean conflict into situated sustainability pathways that privilege human needs, justice and equity. We first outline the promise and limits of prevailing ocean/coastal governance practices, with a focus on marine spatial planning (MSP), which by framing conflict in shallow terms as use incompatibility, supports resolution strategies that privilege neoliberal technocratic-managerial and post-political models of consensual negotiation, thereby obscuring the structural inequalities, maldistributions and misrecognitions that drive deep-seated conflicts. Next, the distinctive features of the marine realm and ocean conflict are explained. Third, we outline the root causes, drivers and scale of conflict, with reference to history, climate, culture, governance, institutions and prevailing international socio-political conditions. Fourth, we reflect on the nature of conflict, exploring implications for shallow and deeper approaches of handling conflicts. Fifth, we highlight the implications of knowledge co-production for understanding and transforming conflict in pursuit of justice. Then, in response to the orthodoxies of MSP and prevailing conflict resolution strategies, we elaborate an alternative approach – Pragmatic Agonistic co-produced Conflict Transformation (PACT) for sustainability – sketching out key elements of a praxis that seeks to transform destructive interaction patterns of conflict into co-produced, constructive, scalable and ‘institutionalizable’ yet contestable and provisional sustainability knowledge-action.