What devices are used for taking depth soundings?

Fathometers are specialized devices used for measuring the depth of water by sending sound waves from the surface to the bottom and measuring the time it takes for the echoes to return. This technique is based on the principles of sonar (sound navigation and ranging). Fathometers operate specifically in maritime contexts to help navigate vessels, understand underwater topography, or locate submerged objects.

While sonar technology underlies how fathometers function, the term "fathometer" specifically refers to the tool designed primarily for depth soundings. Other options like radar are utilized for detecting objects and measuring distances above water, while gyroscopes are used for orientation and navigation but do not provide depth measurements. Thus, the fathometer is the most accurate and direct device when it comes to measuring underwater depth.