Specialists of the Silent Service -- the submarine fleet of the U.S. Navy-- eye their gauges and instruments with calculating care as their ship slides through the dark water eighty feet below the surface. Heart of the undersea vessel, the control room contains the giant wheels which operate the diving planes. Here also is the "Christmas Tree",where green or red lights, constantly gleaming and blinking, reveal whether valves and hatches are safely rigged for diving. At the right a "talker" inputs vital information to other parts of the ship, while at the left a crewman goes up the ladder to the conning tower, located just above the control room.