The unique geological formation near the border with Brunei was the reason for the establishment of Gunung Mulu National Park. This area contains karst caves and cola rocks reminiscent of tall, narrow pillars that spring from the jungle greenery. Many expeditions explored this area, but only in the first half of the 20th-century passages to the caves were discovered. The final findings were made by scientists who spent 15 months in 1977 and 1978 collecting data on this gem of nature. After these scientists, twenty more expeditions studied and discovered new caves in this area. It has led to the fact that Gunung Mulu National Park is the most studied karst area in the world, with 295 kilometers of explored caves.