Mammoth Cave, Show cave in Leeuwin-Naturaliste National Park, Western Australia

Mammoth Cave is a limestone cavern in Western Australia that extends hundreds of meters underground and descends roughly 100 feet (30 meters) below the surface. The cave system sits within Leeuwin-Naturaliste National Park and forms part of the region's natural landscape.

European settlers discovered the cave around 1850, and Tim Connelly led early tours using lamplight to navigate the passages. Electric lighting was installed in 1904, changing how visitors experienced the underground space.

The cave lies in Wardandi Noongar country, and the surrounding karri and marri forest provided food, medicine and materials. The name Mammoth Cave was given by European settlers, referring to the size of the chambers rather than to any mammoth, an animal never native to Australia.

The cave lies 21 km south of Margaret River within Leeuwin-Naturaliste National Park, reached via Caves Road. Entry is through the eastern entrance, and the exit is on the western side of Caves Road, so the route runs one way through the chambers. The floor is rough and uneven, with a narrow pathway and handrail leading upward to the right.

The cave has yielded fossils of Pleistocene fauna over 35,000 years old, including thylacines and the giant marsupial herbivore Zygomaturus. Tim Connelly, the first explorer, was appointed caretaker and led lamplight tours until electric lighting arrived in 1904.