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 below the main flat between 77 and 82 stations, this space being irreverently known as the snake pit. He is looking aft, to starboard and up from the centreline at 78 station showing a mass of pipework and valves under the starboard 16 cylinder Admiralty Standard Range diesel engine. A hinged drop-down front locker is in the bottom of the picture. The ladder leading up to the main flat is on the left. A vertical format negative.