For the hundreds of millions of people living in coastal regions around the world, rising seas driven by climate change pose a direct threat. In order for authorities to plan appropriate protection strategies, accurate information on sea-level rise close to the coast is imperative. For various reasons, these measurements are difficult to get from satellites. However, new ESA-funded research demonstrates how a specific way of processing satellite altimetry data now makes it possible to determine sea-level change in coastal areas with millimetre per year accuracy, and even if the sea is covered by ice.