Milky blue water, black lava and clouds of steam: the Blue Lagoon on Iceland's Reykjanes Peninsula is one of the most photographed places in the country. It sits in the Illahraun lava field about 20 km from Keflavík International Airport and 5 km from the fishing town of Grindavík, which makes it an easy first or last stop on a trip to Iceland.

Steam rising over pale-blue water at Iceland’s Blue Lagoon

How the Blue Lagoon was formed

The lagoon was never planned. In 1976 the Svartsengi geothermal power station began drawing hot fluid from about 2,000 m below the lava field to produce electricity and hot water for the towns of the peninsula. The used water was released onto the lava, and because it is rich in silica, it sealed the porous rock instead of draining away. Pools formed, and the lagoon was born.

In 1981 a local man with psoriasis bathed in the warm runoff and reported that his skin improved. Word spread, the first bathing facility opened in 1987, and the Blue Lagoon company was founded in 1992. Today the spa, its hotels and the power plant are all part of the Svartsengi Resource Park, a showcase for how Iceland uses its geothermal energy.

Bathing areas and walkways among dark lava at the Blue Lagoon

What makes the water blue and milky

The geothermal fluid starts as seawater that seeps into the bedrock, mixes with fresh groundwater and is heated deep underground. The lagoon's water is roughly 70 percent seawater and 30 percent fresh water, with a salt content of about 2.5 percent and a pH of around 7.5.

Its colour comes from silica. Fine silica particles scatter sunlight and reflect the blue part of the spectrum, while the white silica mud on the bottom gives the water its milky look. Blue-green microalgae also thrive in it, and the mineral-rich water is hostile to ordinary bacteria, so no chemicals are added. The lagoon renews itself about every two days, and the bathing area stays at a comfortable 37 to 39 °C all year, even when snow is falling.

Bathers in the steaming geothermal spa

Living with the Reykjanes eruptions

Since late 2023 the Blue Lagoon has had a volcano for a neighbour. A seismic swarm in October 2023 led to the evacuation of Grindavík in November, and a series of eruptions along the Sundhnúkur crater row followed in 2024. The spa closed during each eruption, and protective earth walls were built around Svartsengi and the lagoon. On 22 November 2024 lava crossed the access road and destroyed the car park, but the barriers held and the spa reopened.

The lagoon publishes the current situation on its seismic activity page. Check it, and the Icelandic Meteorological Office, a day or two before your visit.

Planning a visit

Entry is by pre-booked time slot, and tickets often sell out in summer, so book ahead. Packages range from basic entry with a silica mud mask to options with extra masks, a drink, towels and robes. The resort also includes the Silica Hotel, the Retreat Hotel and the Retreat Spa, plus restaurants that look out over the lava.

Because the airport is so close, many travellers bathe on arrival or before their flight home, and buses run between Reykjavík, Keflavík and the lagoon. Allow at least three to four hours in total for changing, bathing and the transfer. A few practical tips:

  • Shower before entering the water; this is the rule at every Icelandic pool.
  • Put conditioner on your hair and keep it out of the water if you can, as the silica leaves it stiff.
  • Drink water while you bathe; the in-water bar is never far away.
  • Winter visits in the dark, with steam and perhaps the northern lights overhead, are some of the most atmospheric.
Blue Lagoon geothermal spa, Reykjanes Peninsula, Iceland – view 4
Blue Lagoon geothermal spa, Reykjanes Peninsula, Iceland – view 5
Blue Lagoon geothermal spa, Reykjanes Peninsula, Iceland – view 6

Blue Lagoon on video

This short film shows the lagoon, the steam and the lava field around it.

Sources