Sonar systems use transducers to transmit an acoustic pulse of sound into the water. When the pulse of sound comes in contact with the seafloor, some of the sound reflects off the seafloor and returns to the ship as an “echo.” The time elapsed between the sound transmit and receive is used to calculate depth of the seafloor. A multibeam sonar system, like the one on the Okeanos, uses multiple transducers pointing at different angles on either side of a ship to create a swath of signals.

In this animation, a survey ship uses a multibeam sonar to measure the depth of the seafloor. The warm colors (red, orange, yellow) correspond to shallower water depths, while cooler colors (green, blue, purple) indicate deeper depths.