team was dispatch to Mulu Caves for 4 months. In this expedition, Sarawak chamber, which lies in the Gua Nasib Bagus was discovered. In 1984, Gunung Mulu was designated as ASEAN Heritage Park. In 1985, the park was officially opened to public. In a British expedition in 1988, a link was established between Clearwater Cave and Cave of the Winds, extending the Clearwater Cave to , claimed to be the longest cave passage in Southeast Asia. Blackrock Cave was also discovered during this expedition. In 1991, a connecting passage was discovered between Blackrock Cave and Clearwater Cave, extending the Clearwater Cave passage to and making it the 7th longest cave passage in the world. Between 1993 and 2000, British expedition teams explored the eastern flank of Mount Api with several discoveries made in the Hidden Valley. Between 1995 and 2000, an American expedition team from National Speleological Society surveyed Gunung Buda (Mount Buda). During these expeditions, Deliverance Cave was discovered. In 2000, Gunung Mulu national park was declared a UNESCO World Heritage Site. Covering an area of , it is the largest national park open to tourists in Sarawak. In 2001, Gunung Buda National Park was gazetted by the Sarawak government. Since 2000, British expedition teams have shifted their focus to explore the caves around Mount Benarat. As a result, Whiterock cave (at Mount Api) was discovered in 2003. In 2005, Whiterock cave was linked to the Clearwater cave system, further extending the system to ; Api Chamber was also discovered during the same expedition. Subsequent explorations were focused on unearthing more hidden passages in the Whiterock cave. In 2017, Whiterock Cave was measured to and Clearwater Cave was measured to . Geography Gunung Mulu National Park is the most studied tropical karst area in the world. It has 295 km of explored caves which houses millions of bats and swiftlets. The national park is located at from Brunei, lies between the headwaters of Tutoh river and Mendalam river where the latter is a tributary of the Limbang River. The western side of the park are lowland area (38% of the park) and the eastern side are the mountain ranges consists of limestone and sandstone. The landforms in the park consists of rugged summits, steep ridges and escarpments, sheer cliffs, gorges, karst towers, caves and terraces, hot springs, floodplains and waterfalls. The park is dominated by three mountains: Mount Mulu