Over half of humanity lives near a coast, and rising seas and flooding are pushing researchers to ask whether cities could simply float instead of retreat inland. This DW film tours the projects testing that idea, from floating homes in Copenhagen to modular island housing in the Maldives and a smart island development in Seoul. Engineers and architects explain designs meant to survive changing water levels, including flexible neighborhoods that can expand, contract, or relocate like a fleet of ships, and the film visits the world's first underwater greenhouse as a model for feeding a waterborne population. Interviews with the researchers behind these projects lay out the practical obstacles: which country's laws apply on open water, how to protect structures from tsunamis, and what floating infrastructure does to marine ecosystems nearby. The film treats floating cities as a serious engineering question rather than a novelty, weighing genuine climate pressure against the legal and environmental gaps nobody has yet solved.