Ásbyrgi

Where it sits. Ásbyrgi is a horseshoe-shaped canyon in Iceland's far northeast, opening toward the sea some 60 kilometres east of Húsavík and 30 kilometres north of Dettifoss. It measures roughly 3.5 kilometres from mouth to head and just over a kilometre across, with sheer cliffs of columnar basalt rising 90 to 100 metres on three sides. Down the middle runs Eyjan — the Island — a flat-topped rock outcrop about 250 metres wide that splits the canyon into two arms for most of its length. The site lies within the Jökulsárgljúfur section of Vatnajökull National Park and is entered from Route 85, the northern coast road, at the visitor centre Gljúfrastofa.

How it was made, twice. The canyon is not a river valley in any ordinary sense; nothing that flows here now could have cut it. Ásbyrgi was carved by jökulhlaups, catastrophic glacial outburst floods that swept down the Jökulsá á Fjöllum when meltwater burst out from beneath the Vatnajökull ice cap, most likely triggered by subglacial volcanic eruptions. Geologists identify at least two major events, the first roughly eight to ten thousand years ago and a second around three thousand years ago, each releasing a discharge of a scale not recorded in modern times. The floods plucked out columnar basalt in blocks rather than grinding it, which is why the walls are vertical and clean-edged. Afterwards the river shifted eastward to its present course, leaving the canyon dry.

The Norse explanation. Long before glaciology arrived, Icelanders had a better story. Ásbyrgi's outline was said to be the hoofprint of Sleipnir, the eight-legged horse of Óðinn, who set one foot down here while galloping across the sky. The name itself means shelter of the Æsir. A parallel tradition, still repeated in the district without irony, holds that the cliffs are the capital of the huldufólk — the hidden people — with the largest population living in the rock at the head of the canyon. Both readings persist in local naming, and the national park's own interpretation panels give the folklore alongside the flood chronology rather than instead of it.

What grows and nests here. Sheltered from wind on three sides, Ásbyrgi holds one of Iceland's more substantial natural birch woodlands, with downy birch, willow, rowan and a dense understorey of crowberry and bilberry. Plantings of pine, spruce and larch were added from the late 1940s and now form tall stands near the campsite, which makes the walk in feel unlike almost anywhere else in the country. At the head of the canyon lies Botnstjörn, a small spring-fed pond ringed by ferns and angelica, with mallard, wigeon and teal on the water. The cliffs above hold nesting fulmars, which is worth noticing: fulmars are seabirds, and this colony sits well inland, one of the odder distributions in Icelandic ornithology. Ravens and gyrfalcon are seen along the rim.

Walking it. From the main car park a level gravel path of about a kilometre runs to the wooden platform at Botnstjörn, which is the shortest and most rewarding walk in the park. The Eyjan circuit climbs the outcrop and follows its rim for roughly five kilometres, ending at a viewpoint that looks straight down the length of the horseshoe — the only way to grasp the shape from inside. Klappir and Kúahvammur add shorter loops through the woodland. The long-distance route south to Dettifoss covers about 30 to 35 kilometres over two days, with an overnight at Vesturdalur, passing the twisted lava columns of Hljóðaklettar and the red scoria craters at Rauðhólar. Trails are marked, but the canyon floor is stony and roots make sections uneven.

On screen, and what is genuine here. Iceland's northeast is heavily used by film crews, and Ásbyrgi's enclosing walls have appeared in commercials, music videos and documentary work; the park requires filming permits and restricts vehicle access off the marked tracks. It is worth being clear about what is authentic and what is imported. There is no Viking settlement in Ásbyrgi and no reconstructed longhouse, and the television series that fixed the modern image of Norse life, Vikings, was filmed in Ireland rather than in Scandinavia or Iceland. What Ásbyrgi preserves is older and less staged: a landform that Norse settlers explained by attributing it to a god's horse, still legible in the place name a thousand years later.

Practicalities. Gljúfrastofa at the entrance has exhibitions, rangers, maps and toilets and opens from spring to autumn. The campsite among the trees is one of the most sheltered in northern Iceland. Route 85 is paved and open year-round, and the canyon is about 65 kilometres from Húsavík by car, though public transport is thin outside the summer months.