CentralNotice From Wikipedia, the free encyclopedia Jump to: navigation , search Present day Earth bathymetry (and altimetry ). Data from the National Geophysical Data Center 's TerrainBase Digital Terrain Model . Bathymetry is the study of underwater depth of lake or ocean floors . In other words, bathymetry is the underwater equivalent to hypsometry or topography. The name comes from Greek βαθύς ( bathus ), "deep", [ 1 ] and μέτρον ( metron ), "measure". [ 2 ] Bathymetric (or hydrographic ) charts are typically produced to support safety of surface or sub-surface navigation, and usually show seafloor relief or terrain as contour lines (called depth contours or isobaths ) and selected depths ( soundings ), and typically also provide surface navigational information. Bathymetric maps (a more general term where navigational safety is not a concern) may also use a Di...