bathymetry

see also:

(bathymetric measurements)

The term bathymetry refers to the surveying of the topographic shape of seabeds and water beds. Whereas in the past, the creation of bathymetric maps relied exclusively on surveys using handheld lead solders or depth sounders, nowadays LIDAR systems make it possible to create precise 3D images underwater much more efficiently. Due to the strong refraction of the water, the laser beam is strongly scattered during underwater propagation, which affects image quality.  Furthermore, these measurements are limited to waters with shallow to medium water depth and low turbidity.  

bathymetry

Image: High-resolution multibeam lidar map showing spectacularly faulted and deformed seafloor geology, in shaded relief and coloured by depth, by NOAA Ocean Exploration & Research, licensed under the Creative Commons Attribution-Share Alike 2.0 Generic license.