Totalling 513,120 square kilometres (198,120 sq mi), Thailand is the world's 51st-largest country by total area. It is slightly smaller than Yemen and slightly larger than Spain.
Thailand is home to several distinct geographic regions, partly corresponding to the provincial groups. The north of the country is the mountainous area of the Thai highlands, with the highest point being Doi Inthanon in the Thanon Thong Chai Range at 2,565 metres (8,415 ft) above sea level. The northeast, Isan, consists of the Khorat Plateau, bordered to the east by the Mekong River. The centre of the country is dominated by the predominantly flat Chao Phraya river valley, which runs into the Gulf of Thailand.
Southern Thailand consists of the narrow Kra Isthmus that widens into the Malay Peninsula. Politically, there are six geographical regions which differ from the others in population, basic resources, natural features, and level of social and economic development. The diversity of the regions is the most pronounced attribute of Thailand's physical setting.