History (stolen from Secret Scotland)
Inchindown fuel depot lies in the hills some four miles north of Invergordon, and was constructed in the period 1939-1942, during World War II, as a bombproof fuel oil store for the Royal Navy, and was connected by pipeline to the Royal Navy dockyard, fuel depot, and port facility at Invergordon. The depot was also referred to as Inchindoun, and the Inchindown Admiralty Underground Storage Depot.
Reports indicate that five such stores were constructed around the country at the time: Inchindown, Copenacre, Hartham Park, Monk's Park and Portsdown. Had the German Navy blockaded Britain's ports, these depots would have been called on to provide fuel for the Royal Navy.
The depots stored Furnace Fuel Oil (FFO): Medium viscosity, boiler NATO Code No: F-82; Joint Service Designation: 75/50 FFO. FFO is basically the residue left behind after the fractional distillation of crude oil, and resembles treacle when at room temperature. Phased out by the Royal Navy in favour of diesel fuel in the late 1970s, it was last used by Leander class frigates, Falklands veteran aircraft carrier HMS Hermes, and the Royal Yacht Britannia.
The depot contains six storage cells, five being 237 metres long and 9 metres tall/wide (roughly 800 feet long and 30 feet tall/wide), holding up to 5.6 million gallons, and a smaller sixth tank, 170 metres long. The first tank carries a plaque commemorating the date February MCMXLI (1941). The access tunnels are a mixture of lined (from the portals), and unlined construction at the rear of the cells, where the access panels are located.
These storage tanks are normally sealed and only permission visits are allowed, we chanced our luck and nipped in past as we were in the area, luckily the door was unlocked!
After some initial hesitations I went for the access into the tanks, I am a fat small bastard, so i laid down on the stretcher and was pushed through the pipe. shoulders scrapped sides it was mega tight, but I was in! Sadly I only had my trusty P7.2 with me so the shots didn't come out well enough to post them all, abut another visit with better lighting options will happen!
Thats all there is really, thanks for looking.