Gunnuhver Hot Springs

Gunnuhver

Reykjanes

The main mud pool at Gunnuhver is around 20 metres across, boiling continuously and churning grey-brown clay with a sound somewhere between a roar and a splatter. Iceland's largest mud pool, it is flanked by steam vents you hear before you see. Unusually, the hydrothermal fluids here are seawater rather than freshwater — ocean water percolates through porous lava and is superheated underground. The site sits directly above the Mid-Atlantic Ridge. Boardwalks thread through the active zone and the warning signs are not decorative. In 2014 a rise in mud-geyser activity forced a temporary closure. The Reykjanes Peninsula has experienced heightened volcanic unrest in recent years, so check current access before visiting — straying off the boardwalk can be fatal. The name comes from a legend: a ghost named Gunna was said to have been trapped here by a priest around 400 years ago. Gunnuhver is about 20 minutes from Keflavík Airport — a convenient first or last stop. The nearby Reykjanesviti lighthouse is a short walk away. Entry is free, the road is paved, and it is open year-round.

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