Bathymetry

Bathymetry is the measurement and mapping of seafloor depth, the underwater equivalent of topography. Modern surveys use multibeam echo sounders for full-coverage swath mapping, single-beam sounders and airborne lidar in shallows, and satellite-altimetry gravity inversion for the deep ocean where ships are sparse. Compilations such as GEBCO grid the result globally; the Seabed 2030 project aims to map the entire ocean floor by 2030.