Depth finder and Echo sounder

Depth finder noun - Navigational instrument used to measure the depth of a body of water (as by ultrasound or radar).

Echo sounder and depth finder are semantically related in sounder topic. In some cases you can use "Echo sounder" instead a noun phrase "Depth finder".

Echo sounder noun - A measuring instrument that sends out an acoustic pulse in water and measures distances in terms of the time for the echo of the pulse to return.

Depth finder and echo sounder are semantically related in sounder topic. You can use "Depth finder" instead a noun phrase "Echo sounder".