They include attractions as diverse as the Great Barrier Reef Marine Park, the Uluru-Kata Tjuta National Park (which includes Ayers Rock) in the arid red heart of Australia, and the temperate Tasmanian Wilderness World Heritage area.

ECONOMIST: A survey of Australia

Climbing the six Abels in the brutal Western Arthurs Range, located inside the World Heritage-listed Tasmanian Wilderness Area that covers 20% of the island, necessitates a walk through such difficult mountain terrain that it can take walkers up to two weeks to hike what is often described as the most difficult bushwalk in Australia.

BBC: Tasmania's greatest mountain quest