This special issue focuses on how the Blue Economy development modelimpacts on coastal livelihoods and sea sustainability in Tanzania. The BlueEconomy discourse tends to be framed in optimistic rhetoric of newopportunities for development, promising a triple-win scenario of economicgrowth, improved livelihood and marine protection. But socioeconomicrealities on the ground offer a more nuanced appraisal of the challenges andopportunities involved. This multidisciplinary special issue interrogatescritical aspects of development in the Blue Economy, focusing on both socialand environmental sustainability. The articles draw on recently concludedempirical research on how coastal communities relate to the ocean, as partof the research project Swahili Ocean Worlds. Fishing Communities and SeaSustainability in Tanzania (2022–2024). The studies presented here cover avariety of topics explored by the research team: coastal livelihoods, women’snarratives and inclusion, aquaculture and entrepreneurship, changing fishingpractices and cultural expressions of music. When analysing their findings,the authors draw on their knowledge in the disciplines of anthropology,creative arts, development studies, geography and sociology, thuscontributing to the oceanic turn in social sciences.