In 2000 UNESCO inscribed Gunung Mulu National Park on the World Heritage List.
"superlative natural phenomenon", "exceptional natural beauty" and "aesthetic importance" were just some of the criteria used by the UNESCO in the selection process.
Mulu's landforms cover both limestone and sandstone terrain and are "outstanding examples" of erosional processes on these rocks.
This is the unique geological and topographical background that makes the region so varied and interesting. It is home to caves, pinnacles, ridges, peaks, deeply incised canyons and the world's finest example of a karst collapse feature.
Overlaid on this distinctive background are the rainforest ecosystems in which 17 different vegetation zones have been identified.
Gunung Mulu Park contains "most important and significant natural habitats" with extremely high biodiversity, numerous species found nowhere else in the world as well as species of "outstanding universal value".
The significance of Gunung Mulu National Park from the point of view of science and conservation was officially recognized when it was attributed World Heritage status.