Gunung Mulu

Gunung Mulu National Park near Miri, Sarawak, Malaysian Borneo, is a UNESCO World Heritage Site that encompasses incredible caves and karst formations in a mountainous equatorial rainforest setting. The park is famous for its caves and the expeditions that have been mounted to explore them and their surrounding rainforest, most notably the Royal Geographic Expedition of 1977 - 1978, which saw over 100 scientists in the field for 15 months.
Within Gunung Mulu National Park is the world's biggest natural enclosed space - Sarawak chamber, found in Gua Nasib Bagus. It is 2,300 feet (700 m) long, 1,300 feet (396 m) wide and at least 230 feet (70 m) high; according to the guides it is big enough to fit St. Peter's Basilica or several jumbojets inside. Other notable caves are Benarat Cavern, Deer Cave, Wind Cave, and Clearwater Cave, which exposes parts of a long underground river going through the park.
Today Mulu continues to retain the sense of adventure associated with its original exploration through the provision of adventure caving and other adventure activities. The primary focus however has shifted to the promotion of an awareness of the significance of the park and its environment through the provision of ecotourism activities that foster understanding and appreciation of the parks values. Accommodation is available at the five star luxury resort Royal Mulu Resort, or there are cheaper lodgings across the river. The park HQ also has limited accommodation.
Mulu is a very inaccessible area; the only practical way of getting to and from it is by air, mainly fromMiri airport. It is possible to travel to the area by riverboat, but it requires a chartered long boat for the last part - and the whole trip by river would take around 12 hours to complete from Miri, while the flight takes only 30 minutes.
The national park is named after Mount Mulu, the second highest mountain in Sarawak