Depth gauge and Echo sounder

Depth gauge noun - A gauge for measuring the depth of grooves or holes or other concavities.

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

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