Jökulsárgljúfur
Jökulsárgljúfur, meaning Canyon of the Glacial River, is a 25-kilometre gorge in northeast Iceland carved by the river Jökulsá á Fjöllum and shaped by catastrophic glacial outburst floods over thousands of years. It forms the northern section of Vatnajökull National Park. The canyon is up to 100 metres deep and 500 metres wide and contains three major waterfalls: Dettifoss, the most powerful waterfall in Europe by water volume; Selfoss just upstream; and Hafragilsfoss downstream. At the northern end of the canyon lies Ásbyrgi, an enormous horseshoe-shaped depression whose sheer walls rise 100 metres and whose floor holds a birch forest and a pond. Norse legend holds it was formed when Odin's eight-legged horse Sleipnir touched the earth. The geological explanation is equally dramatic: a single catastrophic glacial flood carved it in a matter of days.
A 25-Kilometre Canyon Carved by Glacial Catastrophe, Home to Europe's Most Powerful Waterfall and a Horseshoe Canyon from Norse Mythology
Jökulsárgljúfur was formed by the interplay of volcanic activity beneath Vatnajökull glacier and the subsequent release of vast quantities of meltwater in catastrophic glacial outburst floods, or jökulhlaups. Two major flood events, one around 10,000 years ago and another around 3,000 years ago, are responsible for the main canyon structure. The floods were of a scale almost impossible to comprehend: volumes of water that would have dwarfed any modern river discharge tore through the landscape in days, carving the gorge walls to depths of over 100 metres and scouring the valley floor clean. The river Jökulsá á Fjöllum, Iceland's second longest, continues to flow through the canyon today, fed by meltwater from Vatnajökull and carrying fine glacial sediment that gives it a distinctive turbid grey-brown colour. The canyon connects to three volcanic fissure systems, linking it to the active Krafla, Fremrinámar, and Askja volcanic zones.
Dettifoss, at the southern end of the canyon, drops 44 metres over a 100-metre wide lip with a discharge rate of around 193 cubic metres per second, making it the most powerful waterfall in Europe by volume. The falls are accessible from both sides of the canyon via Routes 862 and 864, with the western side (Route 862) giving the classic panoramic view and the eastern side providing a closer approach to the spray. Upstream from Dettifoss, the gentler Selfoss forms a broad, shallow cascade that many visitors overlook in favour of its more dramatic neighbour. Downstream, Hafragilsfoss drops through a narrower canyon section where the basalt walls are particularly vivid. The Hljóðaklettar rock formations, a short drive north, are a series of unusually shaped basalt columns and caves where the curved surfaces create strange acoustic effects and carry sound in unexpected directions. The name means Echo Rocks.
Ásbyrgi at the northern end of the canyon is separated from the main gorge by a section of plateau but is part of the same geological system. The horseshoe formation is approximately 3.5 kilometres long and 1 kilometre wide, with walls rising to 100 metres, and its flat floor holds a birch and willow forest, a small lake, and a campsite. The visitor centre for the Jökulsárgljúfur area is located at Ásbyrgi and is the practical starting point for exploring the canyon from the north. A 34-kilometre hiking trail connects Ásbyrgi to Dettifoss, traversing the full length of the canyon in two to three days with camping at Vesturdalur midway. The canyon is free to enter and accessible by standard vehicle in summer, though some approach roads are unsealed. From Mývatn the drive to Dettifoss takes around 45 minutes.
