This cache is located by the 'Inclined Ramp' (or an inclined cable), which was used to haul up drums of fuel in the six years that Pigeon island was manned as a communications station. You may see these today as stout concrete sleepers about 6 or 7 metres apart up the hill.
Pigeon Island is about 850 metres long and 400 metres wide with an area of just over 18 hectares. Its predominant features are the two peaks joined by a saddle with a spur to the north east running east. On the north side is a rocky cliff about 70 metres high and below this, at the waters edge, is a cave of fair size. The interior of the cave is streaked with interesting colours caused by ground salts leaking through the ceiling. The western side of the Landmark is steep and rocky with only two possible landing slides, used by Admiral Rodney as gun slides (you can see these both on the way up to Signal Peak and on the way up Fort Rodney). The north shore, where the prevailing swells break constantly is of exposed coral. Periodically, these swells reach gigantic proportions and on March 5th 1970 they were recorded as being twenty feet in height. By comparison, the beaches on the southern shore are generally calm and symbolic of tropical island serenity.
More about the Inclined Ramp: (quoted from 'Pigeon Island National Landmark: A Brief History & Guide')
For six years Pigeon Island was manned as a communications station with one or two men on duty round the clock. Fort Rodney was used merely as a foundation for the huge wireless tower erected on top of the fort. The old foundation of No. 2 Battery of Admiral Rodney's day, on the saddle of Pigeon Island, was used for the prefabricated stucco building which housed the two generators, the communications centre and quarters for the men on duty. Running from this building, down to the sea on the east side, was an inclined cable operated elevator for hauling up drums of fuel.