Maehongson, Mae Hong Sorn or Maehongsorn, is one of the northern provinces (changwat) of Thailand, on the country's western border. Neighboring provinces are (clockwise from north) Shan State of Myanmar, Chiang Mai and Tak. To the west, the province borders Kayin State and Kayah State of Myanmar.
Mae Hong Son's nickname is "the city of three mists". It is hemmed in by the high mountain ranges of the Shan Hills and is the most mountainous province in Thailand, occupying 13,814 square kilometres (5,334 sq mi). The province is often covered with mist. Mae Hong Son town was originally established in the early 19th century as an elephant training camp as ordered by the then King of Chiang Mai.