Pamukkale

Pamukkale is an amazing array of hot springs pools that cascade down mountainsides in southwestern Turkey. People have been bathing in them for thousands of years, and it has been designated as a World Heritage Site.
The underground volcanic activity which causes the hot springs also forces carbon dioxide into caves, which was called Plutonium, or the place of the god Pluto. You can also find tadpoles swimming in the pools.