CAVE/KARST FEATURE NUMBER: 5L13
THE THREE SISTERS.
By Peter Horne
The present-day entrance to The Three Sisters cave is a small, gated roof-window lying inconspicuously beside the sealed Glencoe Mile Hill Road near Tantanoola, a little more than half a kilometre from Highway One. Access to the cavern below is not a simple matter of dropping through the one metre-diameter entrance hole; there is an awkward section which needs to be negotiated for about 2 metres before cavers can commence the free drop of around 17 metres or so to the top of a steep dirt-pile. Large masses of fine tree roots hang down like curtains in various areas around the walls of the main 30 metre diameter chamber, and the floor drops away steeply all around, terminating in two patches of water; a small, nasty-looking pool and a much larger and more appealing crescent-shaped lake around the western side.
The Three Sisters has been known by its present name for many decades. The earliest reference found by the author (a copy of a paper by Norman B. Tindale in CEGSA’s Records) was dated September 1933, and it seems to have been known to pre-CEGSA personnel since at least December 1954, when Elery Hamilton-Smith reported that the “… entrance of this cave consists of 3 small holes near the roadside, each approx. 1-2 feet in diameter. From the larger of them, there is a vertical drop of 52 feet to the talus below”. He also noted that “Stalactites (are) plentiful on walls”. June Marlow later noted in May 1958 that a party had entered the cave to survey it, the first time since it had been closed by the district council on an earlier recommendation by CEGSA (reportedly because the hole was used as a dumping ground for carcasses and domestic rubbish and was deemed to be a health hazard). Although they realized that diving could very likely extend the length of the cave under the wall, it was not recommended because the water was murky and contained offal.
The diving potential of The Three Sisters was first recognised in the late 1960s or thereabouts when cave divers re-explored the feature, and in the late 1970s-early ’80s they discovered the large underwater chamber via a (for that time) very nasty restriction. It was only after a couple of years had passed that the general cave diving community became aware of the feature’s existence.
Just beneath the surface of the main lake, the wall cuts back into a flooded alcove, and the ceiling quickly drops to close to the floor, creating a low (0.5m or so) silty restriction which can only be safely negotiated by cave divers who are not a little on the “large side” and who are specially trained and equipped to tackle such conditions. At first glance, this section appears to quickly end, but closer inspection reveals the presence of a narrow vertical drop beside the wall, and this leads back to the left, in a sort of passage, to the top of a large and much more impressive room.
This submerged chamber is roughly circular and perhaps 20 metres across, and it is decorated with many large white limestone slabs. Its maximum depth is around 33 metres, and despite careful searches, no significant extensions have been found to date, although other divers have reported finding a smaller chamber reaching a depth of around 10-15 metres in one area.
The cave has not yet been properly mapped, so it isn’t possible to accurately plot all of its features at this time. (Amended Oct 2003).