Mulu National Park is one of Nature's most spectacular achievements and the 'jewel in the crown' of Sarawak's national parks. It is also the largest national park, covering 52,865 hectares of primary rainforest, which is criss-crossed by fast flowing rivers and clear jungle streams. Mulu is dominated by three mountains - Gunung Mulu (2,376 m), Gunung Api (1,750 m) and Gunung Benarat (1,585 m). Mulu's greatest attractions lie deep below the surface. Hidden underneath the forested slopes of these mountains is one of the largest limestone cave systems in the world.

This system, a breath-taking natural wonder, contains a number of record breaking caves. With the world's largest cave passage (Deer Cave), the world's largest natural chamber (Sarawak Chamber), and the longest cave in Southeast Asia (Clearwater Cave), it is not surprising that Mulu is now world-famous. Over 200 km of cave passages have been surveyed but this is thought to represent just 30-40% of the actual total.

The oldest of Mulu's caves started to form about 5 million years ago when sideways earth movements resulted in the formation of both limestone and sandstone mountains, lying side by side. Millions of years of heavy rain and the action of rivers and running water carved out the vast subterranean system that exists today. The weathering process still continues; dripping water creates new rock features, limestone is slowly worn away, and underground rivers carve and sculpt the caves, transporting limestone debris to the cave mouth or redistributing it within the system.

With its rich bio-diversity, and world-famous caves, Mulu offers the adventurous traveller an exhilarating cave and rainforest experience, possibly unmatched anywhere else on Earth.