The largest river system is the Kapuas in West Kalimantan, with a length of . Other major rivers include the Mahakam in East Kalimantan ( long), the Barito, Kahayan, and Mendawai in South Kalimantan (, , and long respectively), Rajang in Sarawak ( long) and Kinabatangan in Sabah ( long). Borneo has significant cave systems. In Sarawak, the Clearwater Cave has one of the world's longest underground rivers while Deer Cave is home to over three million bats, with guano accumulated to over deep. The Gomantong Caves in Sabah has been dubbed as the "Cockroach Cave" due to the presence of millions of cockroaches inside the cave. The Gunung Mulu National Park in Sarawak and Sangkulirang-Mangkalihat Karst in East Kalimantan which particularly a karst areas contains thousands of smaller caves.