The Blue Lagoon
The Blue Lagoon is Iceland's most visited tourist attraction and one of the most recognisable geothermal spas in the world, set in a black lava field on the Reykjanes Peninsula about 20 minutes from Keflavík International Airport and 45 minutes from Reykjavík. Its milky-blue colour comes from silica dissolved in the geothermal water, which precipitates to the surface as the water cools and scatters light in the blue wavelengths. The water is maintained at 37 to 39 degrees Celsius year-round and is rich in silica, sulfur, and algae. The lagoon was not designed — it formed accidentally in 1976 when wastewater from the adjacent Svartsengi geothermal power plant began flooding a nearby lava field. A power plant employee with psoriasis bathed in it and found it relieved his condition; word spread, and by 1987 the site had been developed for public bathing. The formal spa facilities opened in 1999.
The World's Most Famous Geothermal Spa, Accidentally Created When a Power Plant's Waste Water Flooded an Ancient Lava Field
The Blue Lagoon's origin is one of the more unexpected creation stories of any major tourist attraction. The Svartsengi geothermal power plant began operating in 1976, pumping superheated seawater from 2,000 metres below the surface to generate electricity and hot water for the surrounding communities. The used water, rich in dissolved silica and sulfur, was discharged onto the surrounding 800-year-old lava field. Rather than draining away, it pooled in the porous basalt and formed a warm lake. A local man named Valur Margeirsson, who suffered from psoriasis, asked permission to bathe in the water in 1981 and found that it significantly relieved his symptoms. News of the therapeutic effects spread and casual bathing became common. The site was formalised for public use in 1987, and the Blue Lagoon company was established in 1992. Modern spa facilities opened in 1999 and have been expanded significantly since. Today the lagoon covers around 8,700 square metres and receives over a million visitors a year.
The characteristic colour of the Blue Lagoon results from the high silica content of the geothermal water. As the water cools from its underground temperature of around 240 degrees Celsius to the lagoon temperature of 37 to 39 degrees, silica particles precipitate from solution and form a fine white silt on the lagoon floor and a milky suspension in the water column. These particles scatter light, absorbing the red end of the spectrum and reflecting blue, producing the distinctive azure-white colour. The silica mud can be scooped from the lagoon floor and applied to the skin, and silica-based face masks are offered throughout the bathing area. The water also contains sulfur and blue-green algae, and studies have supported its effectiveness in treating certain skin conditions including psoriasis, eczema, and acne, giving the Blue Lagoon both scientific and anecdotal credibility for its skin benefits.
The Blue Lagoon is on Route 43 on the Reykjanes Peninsula, about 20 minutes from Keflavík International Airport and 45 minutes from Reykjavík by car. Its proximity to the airport makes it one of the most popular first or last stops on an Iceland trip. Three ticket tiers are available — Comfort, Premium, and Retreat — each including lagoon access with progressively more spa services and amenities. Advance booking is essential as daily capacity is strictly managed; walk-ins are not possible during peak periods. The lagoon is open year-round. Note that the Svartsengi area and the nearby town of Grindavík were affected by volcanic activity in 2023 and 2024; check current access status before visiting as conditions in this area can change.
