The sonar sends out signals, or sound waves, that bounce off objects on the sea floor. Returning sound waves, or echoes, are received by the submarine.

The time it takes to receive the echoes tells how deep the object is. Objects that are very deep take longer to return the signals.

The signals that bounce back to the submarine are translated into images by the submarine's computer. Archaeologists use this information to find shipwrecks and other underwater objects.