Umpherston Sinkhole, Mount Gambier

A collapsed limestone cave in the middle of Mount Gambier that was turned into a sunken garden in the 1880s by James Umpherston. Stairs lead down into the sinkhole, where terraced lawns, flowerbeds and hanging vines fill the bowl. It's free and open all the time.

Come back at dusk, when the garden is lit up and brushtail possums come out to feed. The area around Mount Gambier is full of sinkholes and caves; nearby Cave Gardens is another sinkhole in the town centre, and the clear-water sinkholes of Kilsby and Piccaninnie Ponds attract divers and snorkellers.