Kilsby Sinkhole

Meet the site

Kilsby Sinkhole is the one Mount Gambier sinkhole that ordinary Open Water divers can reliably get into, and it is the site most visiting divers remember. The hole is a large collapse doline in Oligocene limestone, walled by vertical grey cliffs hung with ferns and ivy, on a sheep property that five generations of the Kilsby family have farmed. From the pontoon the water drops away in a sheer, clear column – visibility of 50 m is normal and it is often more, so you see the whole bowl of the sinkhole from the surface. Below the lip a slope of rock and silt leads down into the main basin, and a crystal-clear flooded chamber opens off the south-western side, where daylight fades into blue. The upper few metres carry filamentous algae and aquatic weed that glow green in the midday sun, and light shafts pierce the water between about 11 am and 2 pm.

The site has an unusual history. It began as a stock watering hole, was one of Mount Gambier's pioneering dive sites in the 1960s, and was closed after a drowning in 1969. It reopened to civilian divers in 1983, has been used as a training site for SA Police divers and – according to the owners – as a centre for secret weapons research, with the depth and clarity making it ideal for underwater testing. A 2007 lease between the family and the CDAA extended access times and permitted deeper dives on trimix.

Today the Kilsbys also run snorkel tours, dry sinkhole tours, accommodation and gin tastings, so expect other visitors on the rim. For Open Water divers the dive is essentially an introduction to sinkhole diving in a controlled, daylight setting – neutral buoyancy over a bottomless-looking drop is the skill it teaches. CDAA Basic Cave divers use it for deeper, longer dives and photography, and technical divers use it for trimix training. It suits anyone with good buoyancy who wants to see what 'gin-clear' actually means.

What you might see

Very little fish life; freshwater shrimp, yabbies, small native fish near the weed, filamentous algae and aquatic plants in the daylight zone

Location

A large, cliff-walled flooded sinkhole on the Kilsby family sheep farm at Moorak, about 14 km (15 min) south of Mount Gambier; a chamber extends off the south-western side.

Facilities nearby

Parking at the rim, pontoon at water level, toilets and on-site accommodation (villas); gear fills and hire from Dive Experience in Mount Gambier; cafes and supermarkets in Mount Gambier.