A roll film negative. On board the submarine Sealion (1959) towards the end of a long refit at Portsmouth. The photographer is in the aft crew accommodation space between 103 and 117 stations on the main flat looking to port from the centreline at 104 station showing the CO² absorption unit with various valves and gauges against the port side of the boat. The cover of the unit has been removed to show four G.S. Canisters Mk. 2 in position. A telephone and a klaxon horn are against the forward bulkhead at 103 station. A vertical format negative.