The UK Marine Area covers 867,400 km2, 3.5 times the terrestrial extent. Our marine heritage is extraordinary. Shipwrecks from the Bronze Age to the World Wars bear testimony to Britain as an island nation, a destination for trade and conquest and, in the past, the heart of a global empire. Coastal communities have been shaped by their maritime heritage with stories of loss and heroism. Deeper in time, what is now the North Sea was dry land, peopled by prehistoric communities. Our current land would have been distant uplands above hills and plains and rivers now lost and forgotten. Numerous collections represent this heritage, covering 23,000 years, including charts, documents, images, film, oral histories, sonar surveys, seismic data, bathymetry, archaeological investigations, artefacts, artworks and palaeo-environmental cores. These are unconnected and inaccessible. This matters because the story of our seas is of huge interest to the UK public, with millions visiting maritime museums annually, and marine exploitation increasing dramatically for energy, minerals, trade, food and leisure. To unlock new stories and effect sustainable management, we must join up our marine collections. Unpath’d Waters brings together universities, agencies, museums, trusts and experts to confront this challenge. AI is being applied to innovate searching across collections, simulations to visualise landscapes, and science to identify wrecks and research their artefacts. Unpath’d Waters will deliver management tools to protect our most significant heritage and invite the public to co-design new ways of interacting with the collections. The methods, code and resources created will be published openly so they can be used to shape the future of UK marine heritage.