Gunung Mulu National Park

Gunung Mulu National Park near Miri, Sarawak, Malysian Borneo, is a UNESCO World Heritage Site that encompasses incredible caves and karst formations in a mountainousequatorial 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 Geogrhical Society Expedition of 1977–1978, which saw over 100 scientists in the field for 15 months. This initiated a series of over 20 expeditions now drawn together as the Mulu Caves Project.

Gunung Mulu National Park is famous for its limestone kast formations. Features include enormous caves, vast cave networks, rock pinnacles, cliffs and gorges.

Gunung Mulu National Park has the largest known natural chamber or room - 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. It has been said that the chamber is so big that it could accommodate about 40 Boeing 747s, without overlapping their wings. The nearby Deer Cave was, for many years, considered the largest single cave passage in the world.

Other notable caves in this area are Benarat Cavern, Wind Cave, and Clearwater Cave; which contains parts one of the world's largest underground river systems and is believed to be the largest cave in the world by volume at 30,347,540 m³.