This document summarizes a study of the Huai Nam Nak Hot Spring in Tak Province, Thailand. The study examined the hydrogeology and geology of the area. The methodology included analyzing geological maps, topographic maps, and collecting hydrogeological data. Water samples were tested for parameters like temperature, turbidity, pH, and chemical composition. The results found the geology consists of limestone, dolomite limestone and granite intrusion. Travertine deposits were also observed. Groundwater quality was found to be suitable for drinking and below quality standards. The flow pattern of the groundwater was also analyzed. In conclusion, the geology and hydrogeochemistry of the hot spring were characterized.