Clearwater Cave
The 5th longest cave in the world
The Clearwater Cave System (Gua Air Jernih) in Gunung Mulu National Park, Sarawak, Malaysia is believed to be one of the world's largest interconnected cave systems by volume and it is the 7th longest at 265.882 km (165.211 mi) (Nov 2025). The system lies mainly under the western margins of Gunung Api between the Melinau Gorge and Cave of the Winds. The first exploration by speleologists was during the 1977/78 Royal Geographical Society Mulu Sarawak Expedition when 24 km (15 mi) of the cave passage were surveyed. Many expeditions have increased the explored length and will continue to do so for the foreseeable future. The cave's water is clear, completely see-through. It originates from mountain springs and can be drunk without filters. Swimming in the water is authorized when fluvial discharges are low. The cave's water flows in to the Melinau River. There has been expeditions to find a connection between this cave and the Racer Cave (Racer-Easter system) because such a connection would make the whole subterranean complex one of the largest in the planet.
Cave data from Wikidata (CC0). Summary from Wikipedia (CC BY-SA).