Karahnjukavirkjun is a hydropower project in East Iceland, surrounded by a popular reindeer spotting area. It was designed to produce about 4,600 GWh annually to power an Icelandic aluminium smelter in Reydarfjordur.
Karahnjukavirkjun, often called the Karahnjukar Hydropower Plant, sits in the Highlands of the Eastfjords and is the largest hydro project in Iceland. The surrounding area is a beautiful landscape, with good chances to spot wild reindeer in their natural habitat.
The construction of Karahnjukavirkjun in 2009 led to lower flows in the Jokulsa a Dal River, revealing more of Studlagil Canyon, a key location on Eastfjord tours and one of the best places to visit in East Iceland.
It's located close to Egilsstadir, the largest town in the region, and to the popular Wilderness Center.
You can include this stop as part of a broader itinerary with self-drive tours in Iceland, pairing the power station area with the raw beauty of nearby Highland landscapes, or book convenient vacation packages.
Another draw is the Karahnjukar Dam spillway, on the west side of the dam. When active, it showcases the project’s dramatic water handling and Icelandic engineering at scale, and it was famously conquered by a racing driver, Jessica Hawkins, as part of the Range Rover Spillway Challenge in 2022.
Quick Facts
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Project purpose: Hydropower supplying the aluminium smelter at Reydarfjordur.
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Installed capacity: 690 MW at the underground Fljotsdalur Power Station (six 115 MW Francis turbines). Designed energy output about 4,600 GWh per year.
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Dams and reservoirs: Five dams and three reservoirs on Jokulsa a Dal and Jokulsa i Fljotsdal. The main storage is the Halslon reservoir.
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Karahnjukar Dam dimensions: about 193 m high and 730 m long, the largest concrete-faced rockfill dam of its kind in Europe, filled with roughly 8.5 million m³ of material.
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Halslon reservoir: life storage around 2.1 km³; when full it spans roughly 57 km² and stretches up to 25 km.
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Spillway: side-channel overflow weir feeding a long chute; the jet drops around 100 m into a narrow gorge when the reservoir overflows.
What is Karahnjukavirkjun?
Karahnjukavirkjun dams two major glacial rivers, Jokulsa a Dal and Jokulsa i Fljotsdal, with a system of five dams and three reservoirs. Built to supply the aluminium smelter in Reydarfjordur, it produces around 4,600 GWh of electricity each year.
Most visitors are drawn to the central structure known as the Karahnjukar Dam, a concrete-faced rockfill dam standing about 633 feet (193 metres) high with a crest length of roughly 2,395 feet (730 metres). It is the largest dam of its kind in Europe and contains approximately 8.5 million cubic metres of material.
The main storage basin is the Halslon Reservoir, which impounds meltwater from the Vatnajokull region for power generation at the underground Fljotsdalur Power Station (total installed capacity 690 MW).
The Spillway in Iceland: What, Where, and Why It Looks So Dramatic
Many travellers search for “the spillway in Iceland” after seeing a striking video of British racing driver Jessica Hawkins premiering the Range Rover Sport 2022, driving up the side of the dam, through tunnels, and up the dramatic spillway.
That whole video was filmed at the Karahnjukar Dam spillway. It protects Halslon by routing excess water over a side-channel overflow weir and into a long concrete chute that ends at the canyon rim.
From there, a powerful jet drops roughly 100 metres into the narrow gorge downstream. The design lets the reservoir shed seasonal peaks safely, and it only runs during overflow periods.
Spillway Iceland location: the spillway sits on the west side of the Karahnjukar Dam at Halslon in East Iceland’s highlands. When Halslon fills and overtops in late summer or early autumn, a temporary waterfall known locally as Hverfandi can appear at the western end of the dam, plunging into the Hafrahvammagljufur canyon. On strong overflow days, it can look more forceful than many famous waterfalls.
Visiting Tips and Access
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Access road: a paved road (no. 910) runs to the Karahnjukar Dam. Deeper highland tracks and some trailheads beyond the main viewpoints require a 4x4.
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Season and conditions: this is a remote highland setting. Road conditions vary with season and services are limited. Plan fuel, food, and daylight carefully and check conditions before driving.
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Viewing the dam and reservoir: scenic viewpoints around the Karahnjukar Dam and Halslon provide wide views over the reservoir and the upper canyon. The spillway is not always active, so manage expectations outside peak melt and overflow periods.
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On maps, you may encounter multiple names: Karahnjukavirkjun for the overall project, Karahnjukar Dam for the main structure, Halslon for the chief reservoir, and Hafrahvammagljufur for the canyon below the spillway. These terms all refer to the same Highland complex in East Iceland.
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Build your route: include Karahnjukavirkjun as a highlight in East Iceland and connect it with fjord towns or inland tracks in good weather. For easy planning across the region, browse summer self-drive tour packages and select an itinerary that fits your schedule.
Landscape Highlights Around Karahnjukar
The Hafrahvammagljufur Canyon frames the tail end of the spillway jet with near-vertical walls and a wild, secluded feel. When flows are low, the canyon’s colours and textures show through; during overflow, the scene turns thunderous.
History and Debate
Karahnjukavirkjun is one of the most consequential infrastructure projects in Iceland’s modern history.
Supporters point to large-scale renewable electricity and a reliable supply for industry.
Critics emphasise the loss of wilderness habitat for reindeer in Iceland and changes to water systems downstream of the reservoirs.
The discussion has reached a wide audience through books and films exploring environmental trade-offs and the future of Iceland’s highlands.
Plan Your Visit to Karahnjukavirkjun
Karahnjukavirkjun blends raw landscape with major engineering. If you are planning an East Iceland journey, it makes a memorable stop. For itinerary ideas, explore self-drive tour packages and build a route that balances nature, quiet highland driving, and modern energy stories.
Set aside time to take in the views from the dam and the canyon rim. When the spillway runs, the sound alone is worth the detour; when it is quiet, the scale of the highlands speaks for itself. Pack layers, drive thoughtfully, and enjoy a corner of East Iceland most visitors never see.
