Fossil Cave

Fossil Cave (5L81), formerly known as The Green Waterhole, is a cave in the Limestone Coast region of south-eastern South Australia. It is located in the gazetted locality of Tantanoola about north-west of the city of Mount Gambier, only a few metres from the Princes Highway (Route B1) between Mount Gambier and Millicent. It is notable both as a paleontological site and as a cave diving site.
Description and naming.
The cave is formed in 30-million-year-old Oligocene coralline limestone. The cave is a karst sinkhole and is largely filled with water. The surface depression is about long and wide. Beneath the surface it extends to a maximum length of and a width of .
The name of the cave was changed on 23 April 1989 by the Government of South Australia from "The Green Waterhole" to "Fossil Cave" with the change being published in The South Australian Government Gazette on 4 May 1989.
Fossils.
Since the mid 1960s, a variety of Pleistocene subfossil material of birds and mammals has been found and recovered by divers from the surface of a rockpile to a depth of about below the water surface. The probable accumulation mode was by animals drowning when they fell into the cave while attempting to use it as a source of drinking water. Dating of the subfossil remains indicated that their deposition occurred mainly between 15,000 and 40,000 years ago. As well as representing many living animals, examples of extinct species recovered from the cave include the birds "Centropus colossus" and "Orthonyx hypsilophus", and the mammals "Thylacinus cynocephalus", "Thylacoleo carnifex", "Propleopus oscillans", "Macropus titan", "Protemnodon anak", and the sthenurine kangaroos "Procoptodon gilli", "Procoptodon maddocki" and "Simosthenurus occidentalis".
Exploration.
Fossils were first collected from the cave in 1964 followed by a further collection in 1968, a number of expeditions which were organised by the South Australian Museum from years 1968 to 1974 and an excavation carried out by the South Australian Underwater Speleological Society (SAUSS) in 1987.
The cave's submerged extent has been surveyed at least three times including by the Flinders University Underwater Club (FUUC) in 1978, Allum and Garrad in 1979 and the SAUSS in 1987.
Recreational diving.
Fossil Cave is a notable cave diving site. Access for cave diving is limited to holders of the Cave Divers Association of Australia's Advanced Cave grade.