Pilot: Don't look down now buddy.
Passenger: Why, What's our depth?
Pilot: It says -700
ftPassenger: But I can see the sea weed on the floor.
Pilot: Sound moves faster in air than water.
Passenger: Why does that matter.
Pilot: It means that there is air between the sounder and the water.
Passenger: But, but, That means that the boat's not in the water!