This article explores how global ocean governance discourses have been reshaped during the first half of the United Nations’ Ocean Science Decade (2021–2030), with particular attention to the impact of the COVID-19 pandemic and the negotiation of the High Seas Treaty. Drawing on Critical Fantasy Studies and the Nature Futures Framework, we analyse how political fantasies, affectively charged visions that underpin policy action, structure competing imaginaries of future oceans. Through a qualitative analysis of major policy texts, interviews, and participant observations, we identify three dominant fantasies of future oceans: the ocean as saviour, the known ocean, and re-connecting with the ocean. Each offers a distinct vision of future governance, grounded in divergent assumptions about knowledge, nature, and society. We show how these fantasies mobilize political action by combining utopian promises with dystopian fears, and how they sustain or challenge dominant policy trajectories. In particular, we highlight the risk that fantasies of salvation and scientific mastery may perpetuate policy deferrals, while imaginaries grounded in relational values open space for more transformative, justice-oriented governance. Our analysis contributes to growing scholarship on affect, imaginaries, and environmental governance by offering a novel framework for understanding the emotional, ideological, and political investments underpinning international environmental agreements. By examining fantasmatic logics this paper enhances our understanding of why some governance frameworks persist despite limited efficacy, and how alternative imaginaries might open pathways toward more inclusive and transformative ocean governance.