The museum is centred around the former fuel oil pumping station at Lyness Naval Base. The exhibition illustrates the importance of Scapa Flow as a base for the British fleet throughout history, concentrating on its role during two world wars. Although work to build a shore depot for the Royal Navy in Scapa Flow began at the end of 1917, most of the Lyness Royal Naval Base developed between 1937 and 1943. The museum is housed in the former fuel oil pumping station and associated buildings. The Pumphouse, which now forms part of the Scapa Flow Visitor Centre & Museum, was constructed in 1937. Oil was offloaded from tankers and brought through an underground pipeline into the Pumphouse. Steam power was then used to pump the oil into storage tanks through a network of pipes. The Boiler Room houses three Lancashire boilers. Only one of these still has its makers plate, which shows that it was built by Wilson Boilermakers Ltd of Lillybank Works in Glasgow in 1938. The boilers supplied steam at 125 psi and the furnaces are oil fired with steam atomisers. Steam from the boilers was used to power three pairs of triple expansion pumps, housed in the Pump Room. Two of these were built by the Worthington Pump Co. Ltd., London, in 1916 and were originally installed at Port Edgar, a WW1 naval base on the Firth of Forth. The third was built for Lyness by the firms successor, Worthington-Simpson Ltd, Newark, in 1935 and installed here new in 1937 to supplement the other two units. Steam was supplied to the engines at 125 psi and they operated at 28 strokes per minute, with a capacity of 1000 tons per hour. Other exhibits are on display in one of the surface oil storage tanks, which also houses and audio-visual history of Scapa Flow. The former boat store holds a collection of small traditional Orkney craft, plus a boat once used as a floating bank and a motor launch from the German High Seas Fleet which scuttled itself in Scapa Flow in 1919.