Drain the Oceans S02E03 - Killer U-Boats

Using the latest sonar technology, hundreds of shipwrecks around the British Isles are uncovered as victims of World War II's German U-Boats, one of the world's first stealth weapons. Draining the oceans sheds light on this historical event as the secret technology deployed by Germany to sink ships and nearly bring the Allies to their knees is uncovered.