The Blue Lagoon (Icelandic: Bláa lónið) geothermal spa is one of the most visited attractions in Iceland. The spa is located in a lava field in Grindavík on the Reykjanes Peninsula, southwestern Iceland.
The warm waters are rich in minerals like silica. The water temperature in the bathing and swimming area of the lagoon averages 37–39 °C (98–102 °F).
The lagoon is a man-made lagoon which is fed by the water output of the nearby geothermal power plant Svartsengi and is renewed every two days. 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 water heating system. Then the water is fed into the lagoon.