Umpherston Sinkhole / Balumbul

Sinkholes definitely aren't just the stuff of movies and you’ll have front-row seats to Australia’s most spectacular one in Mount Gambier. Umpherston (Balumbul) formed when the limestone roof of a large underground cavern collapsed and with a depth of around 20 metres, it's large enough to swallow a six-storey building. You can marvel at the sprawling greenery that has overtaken the sinkhole from a viewing platform at the top, or descend into the gardens to admire lush foliage, mossy sculptures and beautiful flower beds.