Did you know that the speed of propagation of sound in water is 10 times faster in the air. Sure many times swimming we have heard a noise of a ship’s engine, but when we searched the boat, we see it very remote. For this reason in contrast to the surface, in water sound reaches our ears almost with the same speed and is very easy to guess where the sound comes from.
The speed of sound increases with depth. In the first 50 meters of depth is that the action of the pressure on the speed of sound is minimal, and as the temperature is kept constant, the increase of the speed of sound is little, except that occurs a change of temperature, which will cause a proportional variation in speed.