Fossil Cave

Fossil Cave, originally known as The Green Waterhole, is a significant karst sinkhole located in the Limestone Coast region of south-eastern South Australia. Situated in the locality of Tantanoola, it lies a short distance from the Princes Highway, making it accessible for exploration, particularly for cave divers. The cave is renowned for its dual importance: as a unique paleontological site and as the type locality for exceptionally rare syncarid crustaceans, species of which have only been found in this cave and the Blue Lake near Mount Gambier.

Geological Formation and Description

The cave is formed within 30-million-year-old Oligocene coralline limestone, a testament to the region's ancient geological history. The surface depression of the sinkhole is approximately 20 meters in length and 10 meters in width. Below the surface, Fossil Cave extends considerably, reaching a maximum submerged length of 70 meters and a width of 30 meters. The cave is largely filled with water, contributing to its 'Green Waterhole' moniker before its official renaming.

Paleontological Significance

Fossil Cave has yielded a substantial collection of Pleistocene subfossil material, primarily from birds and mammals, recovered by divers since the mid-1960s. These fossils, dating mainly between 15,000 and 40,000 years ago, provide invaluable insights into the prehistoric fauna of Australia. The accumulation of these remains is attributed to animals falling into the cave, likely while seeking water, and subsequently perishing. Among the significant extinct species identified are the thylacine (Thylacinus cynocephalus), the marsupial lion (Thylacoleo carnifex), and various extinct kangaroo species, alongside extinct bird species like Centropus colossus and Orthonyx hypsilophus.

Exploration and Recreational Diving

Fossil Cave has been the subject of numerous surveys and paleontological operations carried out by cave divers working in collaboration with researchers and institutions such as Flinders University and the South Australian Underwater Speleological Society (SAUSS) Inc. The submerged extent of the cave has been systematically surveyed by various groups over the decades. Today, Fossil Cave is recognized as a notable site for cave diving. However, access for this activity is strictly regulated and limited to divers holding the Advanced Cave grade certification from the Cave Divers Association of Australia, ensuring the preservation of this sensitive environment and the safety of those exploring its depths.