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 to starboard and up from the centreline of the main flat at 89 station showing the air intake pipes at the aft end of the starboard 16 cylinder Admiralty Standard Range diesel engine on the left and the top of the main generator on the right. A canvas screen suspended from the deckhead is lashed and stowed.