Sanya is the southernmost city on Hainan Island, and one of the four prefecture-level cities of Hainan Province in South China.

Hainan is an island province of the People's Republic of China (PRC), consisting of the eponymous Hainan Island and various smaller islands in the South China Sea under the province's administration. It is the southernmost province of China, and the name means "south of the sea", reflecting the island's position south of the Qiongzhou Strait, which separates it from Leizhou Peninsula of the Chinese mainland.