This is Pamukkale Natural Park.

After visiting the traverts, you can stop by this park at the entrance to the Pamukkale Traverts and get some rest. Inside the park there is an artificial lake, two swimming pools and a children's pool. The pools are completely filled with the thermal waters of Pamukkale. There is also a mud bath service for those seeking healing and relief. Other than that, you can walk around the pond, ride a bike, and eat at the restaurant in the park. Or you can just take a short tea break and continue your tour of the ancient cities. If you don't have time to visit all the ancient cities and you want to see the Red Water Traverts, you can continue your tour with the Black Book after the Ancient City of Hierapolis.