The hot spring waters discharging in the Tulehu peninsula of Ambon island; Indonesia, vary in composition from Na-Cl-type to Na-Cl-HCO3-type. Most chemical characteristics of the Na-Cl-type waters are typical of liquids circulating in high-enthalpy geothermal reservoirs. Mixing trends in the plots of alkali vs Cl suggest the existence of a parent geothermal liquid with Cl content of 14,000 mg/kg. The Na-K geothermometer indicates deep temperatures of 230-245 degrees C. The parent liquid cools through conduction and/or mixing with cold, low-salinity groundwaters. Sodium-Cl-HCO3-type waters originate from dilution of the parent liquid accompanied by water-rock interaction under high P-CO2 conditions.