Sanya is on the southernmost tip of Hainan Island, located at 18°09'34″- 18°37'27″ north (latitude), 108°56′30″~109°48′28″ east (longitude). It is adjacent to Lingshui County to the east, Baoting County to the north, Ledong County to the west, and Nanhai to the south. It covers an area of 1919.58 square kilometers.
Sanya borders mountains in the north and the sea in the south. The terrain gradually slopes from north to south, forming a long and narrow polygon. The coastline stretches for 258.65 kilometers, and is the home to 19 harbors. The major ports include Sanya Port, Yulin Port, Nanshan Port, Tielu Port, and Liudao Port. The main bays feature Sanya Bay, Haitang Bay, Yalong Bay, Yazhou Bay, Dadong Bay and Moon Bay. There are 10 major islands, and 40 in total. Sanya has an area of 2 million square kilometers in the South China Sea, with a coastline of 209 kilometers, a sea area of 5,000 square kilometers under its jurisdiction, and a land area of 1919.6 square kilometers.
Downtown Sanya is surrounded by mountains on three sides, with Baopo Ridge to the north, Dahui Ridge, Hubao Ridge and Gaoling Ridge (Gouling) at an altitude of 393 meters to the east, and Nanbian Ridge to the south, forming an encircling terrain with undulating mountains and distinct layers. The extension of the mountain divides the downtown into districts surrounded by green hills, providing unique spatial landscape for the city. Sanya faces the South China Sea, and is the home to many natural bays. The Dadonghai, Xiaodonghai, and Sanya Bay in the downtown are the “must-go-to” places to anyone who travels here.
Sanya is located at low latitude, which enjoys a tropical maritime monsoon climate. The annual average temperature is 25.7°C with the highest in June, reaching an average of 28.7°C; and the lowest in January of 21.4°C. There are 2534 hours of sunshine throughout the year. The average annual precipitation is 1347.5 mm.