Hua Sai is a coastal ditrict in the south of the province on the western coastline of the Gulf of Thailand. Neighbouring districts are (from the south clockwise) Ranot of Songkhla Province, Khuan Khanun and Pa Phayom of Phattalung Province, Cha-uat, Chian Yai and Pak Phanang of Nakhon Si Thammarat Province. The district, established in 1904, is almost entirely dependant on fishing.