Which device is used for measuring the depth of water by sending sound waves down and recording the echo return time?

The device that measures the depth of water by sending sound waves down and recording the echo return time is known as an echo sounder. This technology works on the principle of echolocation. When sound waves are transmitted into the water, they bounce off the seabed and return to the device. The time it takes for the echoes to return is used to calculate the depth of the water based on the speed of sound in water. This is a critical tool in marine navigation, fishing, and scientific research, providing accurate depth measurements that help avoid underwater hazards and assist in various marine activities.

Other devices listed, such as a fathom meter and depth finder, may also be used for depth measurement, but they do not specifically utilize the same echo-sounding technique as the echo sounder. A depth meter can refer to various types of devices but doesn’t necessarily imply the use of sound waves for measurement. In contrast, the echo sounder is explicitly designed for this purpose.