From the World Heritage inscription:
Important both for its high biodiversity and for its karst features, Gunung Mulu National Park, on the island of Borneo in the State of Sarawak, is the most studied tropical karst area in the world. The 52,864-ha park contains seventeen vegetation zones, exhibiting some 3,500 species of vascular plants. Its palm species are exceptionally rich, with 109 species in twenty genera noted. The park is dominated by Gunung Mulu, a 2,377 m-high sandstone pinnacle. At least 295 km of explored caves provide a spectacular sight and are home to millions of cave swiftlets and bats. The Sarawak Chamber, 600 m by 415 m and 80 m high, is the largest known cave chamber in the world.
Not much I can say about Mulu that I haven’t said before. It is the best national park I’ve experienced on my trip and probably one of the most underrated natural attractions on Earth. If you are in the region, take the time to visit Mulu.
The above photo is the entrance to Deer Cave and the Sarawak Chamber, the largest in the world. Each night millions of bats stream out to the rainforest to feed.