[], Mount Api [], and Mount Benarat []. Mount Mulu is a sandstone mountain; meanwhile, Mount Api and Mount Benarat are limestone mountains. The summit of Mount Mulu is covered by moss forests, while the limestone pinnacles are found on the upper part of the Mount Api. The Melinau Gorge separates Mount Benarat from Mount Api. Meanwhile, Mount Buda is separated from Mount Benarat by Medalem Gorge. Mount Buda is included in another national park named Gunung Buda. The national park has three notable caves: Sarawak Chamber, one of the world's largest underground chambers, Deer Cave, the largest cave passage in the world, and Clearwater Cave, the longest cave system in Southeast Asia. The Sarawak Chamber is long, wide and at least high, yielding a volume of and an unsupported roof span of . Meanwhile, the Deer Cave is at to in diameter. As of October 2018, Clearwater Cave has of explored passages. Other caves in this area are Gua Nasib Bagus, Benarat Cavern, and Cave of the Winds. Geology The geology of the park consists of metamorphosed sedimentary sequence of Palaeocene-Miocene age. Mount Mulu is located at the southwest of the park. It was formed from Palaeocene-Upper Eocene with the interbedding of sandstone and shales. The remaining mountains (Mount Api, Mount Benarat, and Mount Buda) are located the western flank of Mount Mulu. These three younger mountains were formed from 40 km band of karstic limestones during the Upper Eocene-Lower Miocene period. It is in this band that the extensive cave system was developed. The cave formation was the result of tectonic uplift of the karst at 2 to 5 million years ago. The caves are typical of the tropical river caves, which exhibits various features such as: elliptical tubes linking different levels of the cave, and speleothem including aragonite and calcite needles. The limestone are either extremely white or grey. The pinnacles on Mount Api are the result of extreme weathering of limestone rocks. The soil in the national park range from peaty-podzolic through red-yellow podzolic to black organic soil. Climate The climate at Mulu national park are affected by northeast monsoon (December to March) and southwest monsoon (May to October). The amount of rainfall is high, which ranges from to . In the lowlands, the temperature ranges from to . At the summit of Mount Mulu, the temperature ranges from to . The climate data shown is