A roll film negative. On board the submarine Sealion (1959) towards the end of a long refit at Portsmouth. The photographer is in the generator room below the main flat between 77 and 82 stations, this space being irreverently known as the snake pit. He is looking forward and down near the centreline showing the combined lubricating oil and fresh water pump against the forward bulkhead at 77 station. On the right is the lubricating oil filter unit. A vertical format negative.