World War II saw an enormous loss of ships and lives at sea. Now, new undersea surveys and 3-D imaging allow the waters to be “drained” away and these sunken wrecks to be examined in detail. From the USS Arizona in Pearl Harbor’s shallows, to Nazi super-ship Bismarck 3 miles down, to the Allies’ D-Day landing and troopship Leopoldville, long-hidden secrets of the deep are revealed.