Mae Hong Son

Mae Hong Son (Thai แม่ฮ่องสอน) (also Maehongson, Mae Hong Sorn or Maehongsorn) is one of the northern provinces (changwat) of Thailand, and at the same time the westernmost. Neighboring provinces are (from north clockwise) Shan State of Myanmar, Chiang Mai and Tak. To the west it borders Kayin State and Kayah State of Myanmar again. It was formerly called Mae Rong Son (also Maerongson, Mae Rong Sorn or Maerongsorn).

Most of the areas of Mae Hong Son Province are complex mountain ranges and likely still pristine virgin forest. Of the approximately 6,976,650 rai of national forest reserves, 88.02% is thought to be pristine virgin forest. Mountain ranges run unbroken from north to south with important mountain ranges being the Lao-territory mountains located on the northernmost portion of the province that serve as a boundary between Thailand and the Union of Burma and the Thanon Thongchai Mountains which are in fact three adjoining ranges, the East, West and Central Thanon Thongchai mountain ranges respectively; the West Thanon Thongchai Mountains serve as a boundary between Thailand and the Union of Burma. The mountains in the east of the province serves as the boundary between the provinces of Mae Hong Son and Chiang Mai. The tallest point is Mae Ya Peak (ยอดเขาแม่ยะ) of the East Thanon Thongchai Mountains in the Pai District in the province's northeast, at 2005 metres above sea level.

Mae Hong Son Province is situated in northern and northwestern Thailand at 17° 38′ - 19° 48′ N and 97° 20′ - 98° 39′ E and furthest from Bangkok in the north at a distance of approximately 924 km. It boasts an area of approximately 12,681.259 km² or around 7,925,812.5 rai, which is third largest in Northern Thailand and seventh largest in the country. It is approximately 250 km from north to south and approximately 95 km from east to west.

To the north and west it connects to a total of three states in the Union of Burma, namely the southern portion of Shan State; Kayah State and Kawthoolei State via the West Thanon Thongchai Mountains and the rivers Salween and Moei which serve as natural boundaries between the countries. To the south it connects to the district of Tha Song Yang, Tak via the rivers Yuam and Ngao which serve as a provincial boundary. To the east it connects to the districts of Wiang Haeng, Chiang Dao, Mae Taeng, Mae Chaem, Hot and Omkoi in Chieng Mai Province via the Central and East Thanon Thongchai mountain ranges that serve as a boundary line between the two provinces.