An international collaboration between US space agency NASA and French space agency Centre National d’Études Spatiales (CNES), with contributions from the Canadian Space Agency (CSA) and the UK Space Agency, the Surface Water and Ocean Topography (SWOT) satellite will measure the height of water in freshwater bodies and the ocean on more than 90% of Earth’s surface. Over the next three years, this information will provide insights into how the ocean influences climate change; how a warming world affects lakes, rivers and reservoirs; and how communities can better prepare for disasters such as floods.