The oceans face a range of complex challenges for which the impacts on society are highly uncertain but mostly negative. Tackling these challenges is testing society’s capacity to mobilise large-scale transformative action and engendering a sense of ‘doom and gloom’. Envisaging positive but realistic visions of the future, and considering how current knowledge, resources, and technology could be used to achieve these futures, may lead to greater action to achieve sustainable transformations. The Future Seas project (www.FutureSeas2030.org) aims to leverage interdisciplinary knowledge to improve society’s capacity to purposefully shape the direction of marine social-ecological systems over the UN Decade of Ocean Science for Sustainable Development (2021-2030). Teams comprising researchers across career stages, Indigenous Peoples and environmental managers, collaborated over a series of workshops to develop narrative futures for 12 Key Challenges facing the oceans. We focused the narratives on two futures: our current trajectory based on published evidence, and a more sustainable future, consistent with the UN’s Sustainable Development Goals, which is technically achievable using existing and emerging knowledge. Presentation of Business-as-usual and More Sustainable futures - together - allows communication of both trajectories, whilst also highlighting achievable , sustainable versions of the future. The advantages of the interdisciplinary approach taken here include: (1) integrating different perspectives on actions and solutions, (2) capacity to explore the interactions between Life Under Water (Goal 14) and other SDGs, and (3) cross-disciplinary learning. This approach allowed participants to conceptualise shared visions of the future and co-design transformative pathways to achieving those futures.