Geysir is a famous hot spring in the geothermal area of the Haukadalur Valley in southwest Iceland. Along with Thingvellir National Park and the mighty Gullfoss waterfall, it is one of the highlights of the Golden Circle route.
Why Geysir is famous
Geysir is the proper name of one particular geyser in the Haukadalur Valley. At one time it was the highest-erupting geyser in the world, and because it lay close to mainland Europe, its name came to be used for the whole category of such hot springs.
When it does erupt, Geysir itself can shoot water as high as 70 meters (230 feet) into the air. And although it comes to life very rarely, it is still the geyser that gives the whole area its name and makes it famous all over the world.
Strokkur lies right next to Geysir and erupts regularly every 5–10 minutes. Today it is thanks to Strokkur that the Haukadalur Valley is so popular with tourists. Geysers are a truly unique phenomenon, but the real show comes when they erupt, not when they bubble quietly beneath the surface…
Besides Geysir and Strokkur, the valley also has Smiður, Litli-Strokkur and several smaller geysers. Fumaroles and solfataras are everywhere too – hissing “mini volcanoes” or “volcanic vents” that release hot steam and various gases into the air. Look out for the yellow sulfur stains around the fumaroles: they form when sulfur carried in the volcanic fumes crystallizes. You can read more about fumaroles and other volcanic phenomena in the article Stunning Effects of Iceland’s Volcanism.
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How a geyser erupts
All over the world – and even in volcano-packed Iceland – geysers are a very rare phenomenon. That is because several conditions have to be met at once for a geyser to form and work.
First, there has to be hot rock – most likely volcanic – underground, but fairly close to the surface. Second, water must flow onto this rock all the time: not very much of it, but steadily, seeping through porous underground rock. Third, to keep the water from turning into an ordinary hot spring or fumarole, there has to be an underground chamber that narrows at the top into a tight passage. And all of this has to come together in one place – no wonder there are so few active geysers in the world.
In Haukadalur, the hot igneous rock underground keeps a temperature of about 130 °C (270°F). At the same time, water keeps flowing in and filling the geyser chamber. The bottom layer of water, resting on the hottest rock, heats up fairly quickly until it boils and turns to steam. The bubbles produced in this process rise upward.
At some point, so many steam bubbles form at the bottom that they can no longer break through to the surface. The narrow outlet of the geyser chamber “plugs” them in, and the pressure at the bottom keeps rising.
Because of the peculiar shape of the geyser chamber, at a certain point the steam gathered in the depths can no longer hold up the column of water above it. An “empty” space opens up over the hottest rocks, and after a moment the column of water from above collapses into it. At that moment, tourists gathered at the surface see the water level in the geyser briefly drop by about 0.5–1 m (2–3 ft), as if something had sucked the water down into the Earth.
Now the lower part of the water column falls onto the heated rocks and evaporates very quickly, producing a huge amount of steam and sharply raising its pressure. At the same time, the water column gets lighter by exactly the part that has just evaporated.
The balance of forces is broken, and the steam pressure in the depths easily hurls the rest of the water column high into the air, creating a picturesque eruption of water and steam. Tourists at the surface squeal with delight and applaud…
New water flows in to replace the water that was blasted out, and the whole process starts again from the beginning…
Geysir: practical tips
Geysir is a must-see stop on the Golden Circle, on the northern stretch of Route 35. The drive from Reykjavik takes about 1.5 hours, but on the way it is worth seeing Thingvellir National Park or – if you come from the south – Kerid crater, the town of Fludir and the hot stream in Reykjadalur, all of which are definitely worth a stop.
Along Route 35 there are large parking lots for tour buses, as well as hotels, restaurants and a gas station. For independent travelers, a smaller parking lot for cars is a little farther up, right at the entrance to the geyser area.
Today, Geysir itself looks rather unremarkable (photo below), so the whole show is stolen by its neighbor, Strokkur. Read more about it and watch a video of its eruption in the article Strokkur – the Most Visited Active Geyser in Iceland.
Geysir is usually dormant. Its neighbor, Strokkur, is far more interesting.