how can submarines use echolocation to tell how close they are to the bottom of the ocean?

how can submarines use echolocation to tell how close they are to the bottom of the ocean?
Answer
Brief Explanations:
Submarines emit sound waves. These waves travel to the ocean - bottom and bounce back as echoes. By measuring the time it takes for the sound to travel to the bottom and return, and knowing the speed of sound in water, the distance to the ocean - bottom can be calculated using the formula (d = vt/2) (where (d) is distance, (v) is speed of sound in water, and (t) is time of travel).
Answer:
Submarines emit sound waves, measure the time for echoes to return, and use the speed of sound in water to calculate the distance to the ocean - bottom.