Answer:
Bathymetry
Step-by-step explanation:
Bathymetry (/bəˈθɪmətri/; from Ancient Greek βαθύς (bathus) 'deep', and μέτρον (metron) 'measure') is the study of underwater depth of ocean floors (seabed topography), lake floors, or river floors. In other words, bathymetry is the underwater equivalent to hypsometry or topography.