The term 'bathymetry' refers to measurement of which oceanic property?

• A. Temperature
• B. Salinity
• C. Depth
• D. Current speed

Answer: (C)

Bathymetry is the measurement of how deep the ocean is—the distance from the surface to the seafloor and the shape of the seabed. That’s why depth is the best answer. To measure depth, ships emit sound waves downward; the time it takes for the sound to travel to the bottom and back, along with the speed of sound in water, gives the depth. Modern methods use multibeam sonar to map vast swaths of the ocean floor. Temperature, salinity, and current speed describe the water’s properties or motion, not the seabed’s depth, so they aren’t bathymetry.