Wellington Caves are really dry caves as they are located west of the dividing range. Occasional rains are not enough to explain the existence of those caves, so they were formed long ago, when Australia was far more south to the pole and the climate was much drier. The cave has nice river passages, which are the last remains of a strong cave river. Today the floor is covered with dry earth.

The regular tourist cave tours show a cave, which is called Cathedral Cave. The last chamber of the tour contains the Altar Rock, a 15 m high stalagmite with 32m circumference at the bottom. It is told to be the largest stalagmite in the world. The second cave open for the public is Garden Cave. This cave is famous for its unusual and beautiful cave coral. The third cave open for the public is the old Phosphate Mine. The caves are home to numerous bats, among them a threatened species called bent-wing bat. A troglobiontic crab living in the caves is considered to be a living fossil.

In the Bone Cave, which is only open to scientists, millions of years old fossils have been found. It was discovered in 1830 by the colonist George Rankin, who accidentally fell into the entrance of a cave. There he found piles of bones. Many of them were of enormous size and could not be matched with any known Australian animal. In the same year he and Surveyor General Thomas Mitchell collected more than 1000 specimens. The age of the bones ranges from approximately 30,000 years up to four million years. The extinct species found here are for example marsupial lions (thylacoleo), the diprotodon, giant kangaroos, huge seven metre long carnivorous goanna, other reptiles, and birds. The diprotodon was a herbivorous marsupial and its teeth were well adapted for grazing. It roamed the area during the Pleistocene period. At the entrance of the cave is a sculpture which tries to show its original look.