A roll film negative. On board the submarine Sealion (1959) towards the end of a long refit at Portsmouth. The photographer is in the motor room between 92 and 103 stations on the main flat looking aft from the walkway at 101 station showing the watertight door in the bulkhead at 103 station open. The aft crew compartment is beyond the door. Above the door are two gauges marked 'Decompression chamber pressure', an automatic emergency lantern and a telephone. Locker L11 is under the door. A vertical format negative.