What information is typically provided by a vessel's echo sounder?

The echo sounder is a critical instrument used in navigation that primarily measures the water depth beneath a vessel. It operates by sending sound pulses from the vessel's transducer into the water; these pulses travel down to the seabed and bounce back to the surface. The time it takes for the sound to return is used to calculate the depth of the water. This information is essential for safe navigation, particularly in areas where shallow waters or underwater obstacles may pose a risk.

In contrast, the other options provided do not pertain to the primary function of an echo sounder. Weather conditions are monitored using meteorological instruments, speed over ground is typically determined by GPS or speedlogs, and nearby vessel locations are tracked using radar or AIS (Automatic Identification System). Each of these functions plays a role in navigation, but they do not involve the direct measurement of water depth, which is the specific purpose of an echo sounder.