Surin is a town in Thailand, capital of Surin province, 431 km east-north-east of Bangkok. It is the site of the annual Surin Elephant Round-up. In 2000, Surin had a population of 41,582. In the north of the province is the valley of the Mun river, a tributary of the Mekong. To the south of the province is the Dongrek mountain chain, which also forms the boundary to Cambodia. The central and northern parts of the province are undulating flood plains.