How does an echo sounder works What are advantages and disadvantages of an echo sounder?

An echo sounder uses sound waves to determine the depth of water. The time interval between transmission and the return of a sonar pulse is recorded, based on the speed of sound in water. A disadvantage of an echo sounder is that temperature affects the speed of sound in water, so a warm thermal layer can distort readings. An advantage of using an echo sounder is that it is very quick and also very environmentally friendly.