The water in the Blue Lagoon stays at a consistent temperature of 37–39°C (98–102°F) year-round. This heat is supplied by the Svartsengi power plant, which pumps up superheated water from 2,000 meters below the earth's surface. By the time the water reaches the lagoon, it is mineral-rich and perfectly tempered for bathing, even during Iceland’s freezing winters.

. Known for its milky-blue, mineral-rich waters, it offers a "hot" experience with average water temperatures ranging between 37–39°C (98–102°F) Blue Lagoon Iceland Essential Visitor Information : Pre-booking is as slots sell out daily.

Mara shrugged. "Maybe because it keeps things from going cold too fast. Maybe because the island needs a place to hold everything that would otherwise blow away."

The lagoon's striking color is a result of science, not dye. It is fed by a unique blend of 70% seawater and 30% freshwater that merges 2,000 meters underground under extreme pressure and heat. As this "geothermal seawater" reaches the surface and cools, silica molecules are released, forming a white mud. These silica particles reflect sunlight in a way that gives the water its signature opaque blue hue. History and Discovery