Iceland's World Famous Blue Lagoon

The Blue Lagoon geothermal spa is one of the most visited attractions in Iceland. The steamy waters are part of a lava formation. The spa is located in a lava field in Grindavik on the Reykjanes Peninsula, southwestern Iceland. 

The warm waters are rich in minerals like silica and sulphur and bathing in the Blue Lagoon is reputed to help some people suffering from skin diseases. The water temperature in the bathing and swimming area of the lagoon averages 37–39 °C (98–102 °F). The Blue Lagoon also operates a Research and Development facility to help find cures for other skin ailments using the mineral-rich water.

Source: Wikipedia