Gunung Mulu National Park is famous for its limestone karst formations. Features include enormous caves, vast cave networks, rock pinnacles, cliffs and gorges. Mount Mulu is a sandstone mountain rising to 2,376 m (7,795 ft).
Gunung Mulu National Park has the largest known natural chamber or room – Sarawak Chamber, found in Gua Nasib Bagus. It is 700 m (2,300 ft)) long, 396 m (1,299 ft) wide and at least 70 m (230 ft) 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 is one of the largest single cave passages in the world.