Khao Phra Wihan National Park covers an area of 130 km2 of the Dângrêk mountains in the southeast of the province. Established on 20 March 1998, it is named after a ruined Khmer Empire temple Prasat Preah Vihear (anglicised in Thailand as Prasat Khao Phra Wihan), now in Cambodia, which had been the focus of boundary dispute. The temple faces north and was built to serve the Sisaket region. Earlier maps had shown it as inside Thailand. However, a boundary survey conducted by the French for the Franco-Siamese Treaty of 1907 deviated from the agreed-upon international divide by watershed in order to place the temple on the French (Cambodian) side.