Question

what is the process called when ships use ultrasound to find the depth of the sea? radar infrared sonar

Explanation:

Sonar (Sound Navigation and Ranging) is a technique that uses sound waves (ultrasound in many cases) to navigate, communicate with, or detect objects on or under the surface of the water, including determining the depth of the sea. Radar uses radio waves and is more commonly associated with detecting objects in the air or on land. Infrared technology detects infrared radiation (heat) and is not related to using ultrasound for sea - depth measurement.

Answer:

Sonar