Mountains in south-west of Lake Koycegiz not die at the foot of the historic day of the Thermal Sultani is based on our thousands of years before. BC In 100 years is known to be used by Kaunos. The accommodation facilities were expanded in the Byzantine period have been made. Today, the facilities in the Byzantine period remained below the waters of Lake Koycegiz. Was converted into a comprehensive hospital in the Roman period. According to sources, to the entrance of the hospital "on behalf of the gods of death are not allowed here," he was written. Mountain received its name can not die here. Rheumatism, kidney and urinary tract disorders, metabolic disorders, mental fatigue, skin and gynecological diseases. Thermal water Sultani of the calcium chloride, calcium sulfate, calcium, sulfur, bromide, radon and radioactive material contains. Water temperature is 39 degrees Sultaniye Turkey's highest radioactivity with Hot Springs is a spa (98.3). Because of high radioactivity are rehabilitating features. Treated as invalid after the return of the patients here are said to walk From Dalyan by boat from Koycegiz Sultaniye Thermal can reach the boat or by road.