Gunung Mulu National Park, situated in the Malaysian State of Sarawak on the island of Borneo, is outstanding both for its high biodiversity and for its karst features. The park is dominated by Gunung Mulu, a 2,376 m-high sandstone pinnacle and the property is the most studied tropical karst area in the world. The geological Melinau Formation contains a remarkable concentration of caves, revealing a geological history of over more than 1.5 million years.