The Blue Lagoon ( ) is a geothermal spa in southwestern Iceland. The spa is located in a lava field near Grindavík and in front of Mount Þorbjörn on Reykjanes Peninsula, in a location favourable for geothermal power, and is supplied by water used in the nearby Svartsengi geothermal power station. The Blue Lagoon is approximately from Keflavík International Airport, and is one of the most visited attractions in Iceland. Description The water's milky blue shade is due to its high silica content. The silica forms soft white mud on the bottom of the lake which bathers rub on themselves. The water is also rich in salts and algae. The water temperature in the bathing and swimming area of the lagoon averages . Guests are required to shower bare naked prior to using the geothermal spa. The communal showers are split up by gender. Children age 8 and under are only allowed entry with the use of arm floaters, provided free of charge. The lagoon is not suitable for children under the age of 2 years. The lagoon is accessible for wheelchair users with a ramp that extends into the water and a shower chair. There is also a private changing room available for those with special needs. History Water source The lagoon is man-made. The water is a byproduct from the nearby geothermal power plant Svartsengi where 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. The rich mineral content is provided by the underground geological layers and pushed up to the surface by the hot water (at about pressure and temperature) used by the plant. Because of its mineral concentration, water cannot be recycled and must be disposed of in the nearby landscape, a permeable lava field that varies in thickness from to . After the minerals have formed a deposit, the water reinfiltrates the ground, but the deposits render the ground impermeable over time, so the plant needs to continuously dig new ponds in the nearby lava field. The water renews every 2 days. The average pH is 7.5 and the salt content is 2.5%. Very few organisms live in the water apart from some