June 21 is World Hydrography Day! It is estimated that only 18% of the ocean has been mapped so far, yet the marine environment is changing before we get to fully know it. Autonomous vehicles offer a wide range of possibilities to increase our knowledge. They can be used to reach remote or dangerous areas and are very efficient at gathering information. Up-to-date and accurate digital data can then be used to develop autonomous shipping that is safe and sustainable. World Hydrography Day 2020 celebrates the link between hydrography and autonomous technologies. These include aerial, surface and underwater survey drones, as well as autonomous ships.