The Satun Province is located in the south of Thailand at the border to Malaysia. Its original Malay name, Setul is derived from santol, the wild mangosteen tree. Located at the Andaman Sea, it has numerous marine national parks like Ko Tarutao and Ko Phetra, and a big freshwater swamp area in the Thale Ban National Park. It is separated from Songkhla Province by the Nakhon Si Thammarat mountains and from Malaysia by the Sankalakhiri mountains. There are several limestone areas with tropical tower karst and numerous caves. There are several show caves, mostly open to the public through the UNESCO World GeoPark Satun. Many caves are close to sea level and the karst water table, have cave rivers and are generally not developed and toured by boat or kayak.