World-class scientists are meeting in the Azores on 24-29 September 2018 to discuss the latest developments in our understanding of Earth’s surface variations observed by altimetry. Radar altimeters record the surface topography along the satellite’s ground track. They precisely measure a satellite’s height above water, land or ice by timing the interval between the transmission and reception of very short radar pulses. These measurements are used to monitor changes in sea level and ice height, for example. The opening session of the symposium was streamed, and includes talks on the early development of satellite altimetry, the 25-year record of global mean sea-level change, global ocean circulation, sea-floor mapping, polar altimetry, and more.