Gunung Mulu National Park is famous for its limestone karst 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 worlds largest underground river systems and is believed to be the largest cave in the world by volume at 30,347,540 m³.

Mulu's limestones belong to the Melinau Formation and their age is between 17 and 40 million years (Late Eocene to Early Miocene).

Stratigraphically below the limestones, and forming the highest peaks in the south east sector of the Park including Gunung Mulu, lies the Mulu Formation (shales and sandstones). The age of these rocks is between 40 and 90 million years (Late Cretaceous to Late Eocene).

An amazing national park in Borneo, accessible by plane or boat only. It has some of the world's largest caves - one cave has 3 million bats living in it, and another has a river running through it. See plants found nowhere else in the world. Take a walk on the canopy boardwalk in the tree tops and get a close look at wild monkeys and tropical birds. Meet the indigenous Penan people, who will be your guides in the park. You can also take a boat trip to visit their villages and buy handmade crafts such as woven baskets, carved bracelets, or even a blow gun. For those looking for a challenging multi-day hike through the jungle, try a hike to the Pinnacles (sharp limestone formations), to the summit of Mt. Api, or the Headhunter's trail.

The climb to the summit of Mt. Api is challenging; the rocks are sharp and its uphill the whole way, but the view is worth it. There are some steep bits but ladders and ropes are provided to help.

world heritage location...amazing view of natural cave...the biggest chamber in world is there...worth it..awesome for natural lover..