Karahayit is the quieter spa village north of Pamukkale, known for hot mineral water that stains the rock and pools rusty red rather than white. It is less photogenic than the travertines, but it gives a more everyday view of the thermal landscape that made this area famous.
Come if you want a soak after Hierapolis or if you are curious about the local bathhouse culture. The village is practical rather than polished, with pensions, simple restaurants, and thermal hotels clustered around the springs.