Geothermal area in Seltún
Seltún is a striking geothermal field within the Krýsuvík volcanic zone on the Reykjanes Peninsula, about 40 minutes from Reykjavik. Boiling mud pots, hissing steam vents, and hillsides painted yellow, orange, and red by mineral deposits create a landscape that looks genuinely otherworldly, and a boardwalk trail makes it accessible and safe to explore up close.
Boiling Mud Pots and Mineral Colours on the Reykjanes Peninsula
Seltún sits on the Mid-Atlantic Ridge, where the North American and Eurasian tectonic plates are pulling apart, putting it directly on top of one of Iceland's most active geothermal zones. The Krýsuvík volcanic system that underlies the area pushes heat and gases close to the surface, where groundwater becomes superheated and forces its way out through vents and fissures. The result is a constantly active field of bubbling mud pots, fumaroles releasing jets of steam, and hot springs with surface temperatures reaching up to 100 degrees Celsius. The minerals in the soil, sulphur in yellow, silica in white, iron oxides in red and orange, give the hillsides their vivid and constantly shifting colour. In winter the effect is particularly pronounced, as snow settles everywhere around the site while the geothermally heated ground remains entirely bare.
A well-maintained boardwalk winds through the field, keeping visitors safely above ground that can be dangerously unstable and scalding hot in places. Two viewing platforms sit at different elevations, each offering a different perspective on the terrain. The loop takes around 20 to 30 minutes at a relaxed pace. For those who want more, a marked hiking trail continues beyond the boardwalk and climbs to the Hverafjall ridge above the geothermal area, where the views extend across Kleifarvatn lake and out toward the ocean. That route is around 5.6 kilometres and takes roughly 90 minutes. The German scientist Robert Bunsen visited Seltún in 1845 and it is said his observations of the sulphuric activity here contributed to his later work on gas chemistry.
Seltún is located on Route 42 on the Reykjanes Peninsula, about 35 kilometres from Reykjavik and 40 minutes from Keflavik International Airport. Entry is free and parking is available at the site. There are no facilities on site so it is worth stopping for food and water before arriving. Nearby attractions include Kleifarvatn lake, a deep and moody volcanic lake a few kilometres to the north, and Grænavatn, a vivid green explosion crater lake a short drive to the south. Seltún pairs well with a broader Reykjanes Peninsula day trip that also takes in the Bridge Between the Continents and the Gunnuhver geothermal area near the lighthouse.
