The Sarawak Chamber is a huge chamber in Gua Nasib Bagus (Good Luck Cave), which is located in Gunung Mulu National Park, in the Malaysian state of Sarawak on the island of Borneo. It is considered to be the largest known underground chamber in the world.
The chamber was discovered by three Englishmen in January 1981. Andy Eavis, Dave Checkley and Tony White (all experienced cave explorers) had been exploring the dense, unpopulated area of the Gunung Mulu National Park jungle in Sarawak, in the north of Borneo, in an expedition led by fellow Englishman Ben Lyon. While they were surveying some of the newly found caves in the region, they stumbled into what seemed to be a huge cavern. Even with their powerful lamps, the other end of the chamber couldn't be seen through the thick darkness.
Although they did not know it, the three explorers had walked into the largest known enclosed space in the world, which they later named the Sarawak Chamber. It was three times the size of the Big Room in Carlsbad Caverns National Park, New Mexico, previously thought to be the largest underground chamber. The Sarawak Chamber measured 700 m (2,300 feet) long, 400 m (1,300 feet) wide and at least 70 m (230 feet) high. The chamber is now firmly situated as the largest in the world.
The cave was in a region filled with at-that-time newly-discovered caves in the Gunung Mulu National Park, and this particular one is called Lubang Nasib Bagus or Good Luck Cave. To reach the Sarawak Chamber one must follow the river upstream from the cave entrance. This long passage has a roof of at least 60 metres high, and does require some swimming and a traverse along a ledge. The story of how it was discovered is told in a 1985 book Underground Worlds by Donald Jackson and also in Giant Caves of Borneo by Meredith, Wooldridge and Lyon.
The chamber is due to two main factors. The first of which is uplift in the soil, occurring between 2 and 5 million years ago. The second is the erosion of the soft limestone and other rocks, and coupled with high rainfall of the surrounding rainforest, these processes made the chamber we see today.
