A roll film negative. On board the submarine Sealion (1959) towards the end of a long refit at Portsmouth. The photographer is in the generator room between 77 and 92 stations looking forward from the centreline of the main flat at 90 station showing the port and starboard main generators and the two16 cylinder Admiralty Standard Range diesel engines. The watertight door in the forward bulkhead at 77 station is open. A vertical format negative.