Sometimes just getting to a cave in Queensland is an adventure in itself. Camooweal Caves, for example, within the national park of the same name, lie beyond Mount Isa at the end of a rough road only 8 miles from the Northern Territory border. More accessible is Chillagoe-Mungana Caves National Park, 124 miles inland from Cairns, where guided tours of the magnificent limestone system are available. Cave tours are also offered at Capricorn Caverns, which is situated on private property in the hills north of Rockhampton. Nearby are Cammoo Caves and the caves of Mount Etna, where recently a conservation battle was fought to prevent mining and preserve ghost-bat habitat. For an exhilarating adventure that combines caving and bushwalking, head to the Undara lava tubes – the largest lava tubes in the world, at 100 miles in length – in Undara Volcanic National Park, 162 miles south-west of Cairns.