How are echo soundings used by ships?

Echo sounding is used to get indication of any difference in the properties of the water. Fish finding, and depth sounding would be obvious uses. Other uses including locating enemy submarines or...

Echo is used for instance in sonars to analyze underwater objects or its surface; in music, in small quantities to give a more powerful and surrounding sound, and in computer language to retrieve...

They are used to locate objects by sound bouncing off them.

Commuting is the preferred use.