Mount Gambier (Australia)

I advise you to visit the Umpherston sinkhole, a hole that was created when the ceiling of a cave collapsed. Transformed into an underground garden in 1886, it is open to visitors. Every evening, it gets lively with the presence of possums that come to the sinkhole to feed.

"Blue Lake" and the "Crater Lakes" are also worth a visit as part of the "Volcanoes Discovery Trail". Guided visits leave from the Visitors Centre. The short trail is only 3.6 km and leads you around a particularly colourful lake. You can enjoy the view from many different viewpoints, the most popular is the tunnel under the road between Blue Lake and Leg of Mutton Lake.

The Tantanoola Caves, located on the flank of a cliff, are exposed to the constant erosion of the ocean. This huge dolomite cavern shelters an extraordinary display of rock paintings and light that shimmers between pink and brown. 

Among the other more improbable activities to do in the area: have your picture taken next to a giant crawfish.