Hua Sai is a district in the southeastern part of Nakhon Si Thammarat province, southern Thailand. Neighboring districts are: Ranot of Song…Hua Sai is a district in the southeastern part of Nakhon Si Thammarat province, southern Thailand. Neighboring districts are: Ranot of Songkhla province; Khuan Khanun and Pa Phayom of Phatthalung province; Cha-uat, Chian Yai, and Pak Phanang of Nakhon Si Thammarat Province. To the east is the Gulf of Thailand.