A roll film negative. On board the submarine Sealion (1959) towards the end of a long refit at Portsmouth. The photographer is in the sound room on the starboard side of the main flat between 56¼ and 59¼ stations looking to port and forward showing the compartment sliding door on the left. Alongside the door are a fire extinguisher, an automatic emergency lantern, a sonar intercom switch box and a type 719 sonar intercom mixer unit. Against the forward bulkhead are 300v, 500v, 600v and 750v DC units. A vertical format negative.