echo sounder

noun

1. a sonar instrument that uses echolocation to measure depths under water.

noun

1. a navigation and position-finding device that determines depth by measuring the time taken for a pulse of high-frequency sound to reach the sea bed or a submerged object and for the echo to return

noun

1. an instrument for detecting the depth of water or of a submerged object by means of sound waves; FathometerSee also sonar