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The history of Seltún Geothermal Area

Seltún Geothermal Area forms part of the Seltún Krýsuvík Geothermal Field. Its hot springs, solfataras, fumaroles and mud pools make it an interesting visitor destination, but once you learn a bit about the area’s past, you’ll be even more keen to get there yourself. Let’s take a look at the history of Seltún Geothermal Area.

Seltún’s geological history

Geology tells the story of the past and at Seltún, what a rich and fascinating past that is. Mostly, the rock here is basalt, with examples of post-glacial lava fields, ridges of pillow lava and breccias (rock fragments cemented together) that are proof of past volcanic activity. The most recent eruption at Seltún took place in the 13th century.

One of the most attractive features of the Seltún Geothermal Area is its myriad colours. The landscape here is characterised by a broad spectrum of colours that are especially vivid on a sunny day. It is streaked with white, silvery-grey, brown, red, orange, yellow and even blue – a clear reminder of the area’s varied geology.

Each colour reflects the components in or on the rock. Yellow indicates sulphur, of course, while white marks on the mud pits show they have a high silica content. Blue indicates pyrite concentrations. Meanwhile other surfaces are reddish in appearance thanks to the presence of iron oxides in the rock.

Scientists keep a close eye on places like Seltún. Just as with dormant volcanoes, the area can suddenly spring into life. In 1999, for instance, drilling was taking place in the area which triggered an explosion. This led to the formation of a new, substantial crater vent. Hot water, mud and steam were also ejected during explosions in 2010 and 2019.

For this reason, it’s absolutely imperative to heed warnings should Seltún temporarily be placed on a no-go list. Monitoring technology is typically very accurate, however, and so there’s usually no danger in visiting in other cases.

The importance of sulphur: Seltún’s time as a commercial mine

Iceland’s geology has made it a prime spot for sulphur mining in the past. Seltún was one of two key places in the country where this took place; the other was over on the opposite side of Iceland close to Lake Mývatn.

Nevertheless, the sulphur was tricky to mine, as the deposits were unhelpfully sandwiched between layers of lava. To reach it, workers had to break up the rock first, which was tough and laborious work. Only then could they access the sulphur beneath.

But where there’s a market, it’s worth the toil and trouble. Interestingly, in the Middle Ages, demand for sulphur was high. At that time, it was used in medicines to cure haemorrhoids, get rid of worms and treat skin diseases like psoriasis and leprosy. It was even commonly called upon as a laxative. And you’ve heard of brimstone? It wasn’t only used for medicinal purposes. Later, sulphur’s role as a key ingredient in the manufacture of gunpowder helped keep demand high and ports such as Húsavík busy.

You see, the vast majority of the sulphur that was produced in Iceland was for the export market and didn’t remain in the country. Centuries ago, foreign powers controlled mining operations and trade was buoyant. The Norwegian kings kicked things off in the 12th century, after which the British got in on the act. Later, the merchants of the Hanseatic League saw an opportunity to make money too and it was their turn to oversee this lucrative trade.

By 1561, it was time for another European power to step in. The Danes were in charge of Iceland at that time and they had managed to secure a monopoly in sulphur production, buying out local concerns to rid themselves of competitors. Although by then, deposits weren’t as abundant and the sulphur processing aspect of the business moved out of the country.

The industry, always more heavily concentrated further north where it was more easily exported via the port of Húsavík, slowly wound down. By the 1880s, mining at Seltún was more or less finished. In any case, sulphur doesn’t leave a long-lasting mark on the landscape so today, there is little contemporary archaeological evidence of this time in the country’s history. Perhaps, in a sense, that makes it even more interesting.

Recent history: the challenges of tourism and environmental protection

Even now, ethereal plumes of steam rise from the ground. On cold mornings this place is especially atmospheric to look at. Your nose might be less enthusiastic, however: the smell of rotten eggs hangs on the air as hydrogen sulphide escapes from fumaroles and oxidises into sulphuric acid.

At Seltún, hot, bubbling water on the ground typically reaches temperatures of between 34 °C and 50 °C, though that figure can be much higher. Coupled with the stains of mineral deposits, it creates an extraordinarily photogenic scene and it’s not hard to see why such an area should be valued and conserved.

This raw and dynamic landscape has captured the attention of visitors from all over the world. There’s something extraordinary about being in such a locale. Perhaps it’s the misty setting, where your fellow travellers might momentarily disappear from view and then reappear again in a slightly different location. Or maybe it’s knowing that none of this is the work of people, and that nature herself is responsible for such a curious and breathtaking place.

And there’s another reason to visit: with considerably less footfall than busier sites such as Geysir, there’s still a sense of this being a hidden gem. Although, the place is gaining momentum on tourist itineraries, not least because of the extra attention focused on the wider Reykjanes area following sustained volcanic activity elsewhere on the peninsula. Yet come off season and you might still get the place to yourself, a real privilege.

Today, Seltún Geothermal Area is a protected area – there’s no way sulphur mining would be allowed here today. As you stand and imagine what would have been there in the past, you’re reminded about how people can sometimes have a transitory impact on the world they inhabit.

That said, even tourism can have a negative effect on the fragile ground unless it is carefully managed. Visitors are reminded that they should always stick to the marked paths. Remember, steam can erupt from the ground violently and with little or no warning, so heed any official advice and never stray into areas that are out of bounds. Consider whether you need to walk uphill and be mindful of the impact that many feet can have.

Though visitor facilities are limited and seasonal here, a boardwalk and information signs help you access and make sense of this striking, other-worldly landscape. It truly is a magical place and one you definitely won’t want to miss.