Gunung Mulu National Park, Sarawak

A UNESCO World Heritage Site, Gunung Mulu protects the world's most extensive cave system, the Sarawak Chamber (the largest underground chamber on earth), the spectacular Deer Cave bat exodus involving up to 3 million bats, and the razor-edged Pinnacles karst formation in a park that has been described by Sir David Attenborough as the most biodiverse place he has ever visited.