Pamukkale, Denuzli, Turkey
The tiered travertine pools of Pamukkale (“Cotton Castle”) are picture perfect – so beautiful, in fact, that they’re Turkey’s most-visited attraction. The UNESCO World Heritage site is also the location of the well-preserved ruins of the ancient Greek/Roman city Hierapolis. Only one pool is open to the public: paddle between ancient submerged columns in the mineral-rich waters.