In the Pacific Islands, whose people contribute the least to global warming, but are facing its most severe effects, impacts from climate change are far from a future scenario. Here, in the great maritime region of Oceania, the future is today. Sea-level rise and erosion of land combine to create a challenging situation not documented historically: entire nations risk the partial or total loss of their land, and the fate of their ocean territories as Exclusive Economic Zones defined by extent from the land may be uncertain. There may also be challenges to the citizenship of those states whose low-lying islands are at threat. In this situation the countries of the Pacific represent themselves as Big Ocean States as a powerful alternative to the UN category of SIDS (Small Island Developing States), and engage in global diplomacy and activism to safeguard their ocean. The Island Lives, Ocean States (OceanStates) project aims to build new and urgent interdisciplinary analysis of one of the greatest challenges of our time: how Pacific islanders and their states work to protect their sovereign land and sea territories from the uncertainties and threats caused by climate change.