Bathymetry - the foundation for sustainable seas, oceans and waterways

 The term combines the Greek words bathus, meaning "deep," with metron, "measure.

World Hydrography Day commemorates the June 21, 1921, establishment of the International Hydrographic Organization. In 2005, the United Nations formally adopted the resolution for IHO member countries all over the world to celebrate WHD on the 21st of June each year. WHD is an opportunity to increase awareness of hydrography and its vital role supporting the safety of navigation mission and the maritime environment.