A roll film negative. On board the submarine Sealion (1959) towards the end of a long refit at Portsmouth. The photographer is in the crew's washplace between 73 and 77 stations on the port side of the main flat looking up at the deckhead showing a number of handwheel valves, a ring main pressure gauge, a sonar type 185 cable changing box No. 1 topside transducer, a light and two mirror light switches.