The 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 warm waters are rich in minerals like silica and sulfur and bathing in the Blue Lagoon is reputed to help some people suffering from skin diseases such as psoriasis. The water temperature in the bathing and swimming area of the lagoon averages 40 °C.
The lagoon is fed by the water output of a nearby geothermal power plant. Superheated water is vented from the ground near a lava flow and used to run turbines that generate electricity. After going through the turbines, the steam and hot water passes through a heat exchanger to provide heat for a municipal hot water heating system. Then the water is fed into the lagoon for recreational and medicinal users to bathe in.
The spa is located in a lava field in Grindavík on the Reykjanes Peninsula, southwestern Iceland.