A roll film negative. On board the submarine Sealion (1959) towards the end of a long refit at Portsmouth. The photographer is in the auxiliary machinery space between 62 and 68 stations below the main flat looking to port and forward from the port side at 64-65 stations showing pipework, valves, an electric motor and a pressure gauge. On the right is a panel marked 'Battery cooling pump starter (port) C4-5' and in the left background is a unit marked 'Battery cooling pump indicator'.