Þórsmörk

Where it sits. Þórsmörk, Thor's wood, is a valley system in the southern Icelandic highlands enclosed by three glaciers: Eyjafjallajökull to the southwest, Mýrdalsjökull to the southeast and Tindfjallajökull to the north. The braided glacial river Krossá runs through the middle of it, and steep ridges of palagonite and moss-covered scree rise on all sides. The shelter those ridges provide creates a genuine microclimate — warmer, calmer and drier than the coastal plain 30 kilometres south — which is why birch woodland survives here in a country that lost most of its forest cover centuries ago. Strictly speaking Þórsmörk is the area north of the Krossá, with Goðaland and Almenningar as its neighbours, but the name is used loosely for the whole basin.

Getting in, which is the entire problem. No paved road reaches Þórsmörk. The F249 leaves Route 1 near Seljalandsfoss and runs about 30 kilometres inland, crossing a series of unbridged glacial rivers, of which the Krossá is the last and by far the most serious. Its channel shifts daily, depth changes with sun and rain, and it has swallowed a long queue of rental vehicles. Standard rental insurance in Iceland explicitly excludes water damage from river crossings, so a mistake here is paid for in full. The sensible route is the highland bus, which runs daily in summer from Reykjavik, Hvolsvöllur and Seljalandsfoss in vehicles built for the fords. Only large, high-clearance four-wheel-drives with an experienced driver should attempt it privately, and never alone.

On screen. Þórsmörk supplied Game of Thrones with terrain for the lands beyond the Wall. Stakkholtsgjá, a canyon on the approach road, is the location most often identified with the series here: a gorge roughly two kilometres long and up to 100 metres deep, ending at a waterfall in a mossy chamber, and it has been widely reported as one of the settings used for the ranging sequences in the seventh season, filmed in the Icelandic winter of 2016 and 2017. As with all of the show's Iceland work, the finished shots combine the real gorge with glacier plates and digital extension, so the canyon on screen is snowier and larger than the one on the ground. The walk in from the parking area takes 30 to 45 minutes each way over stepping stones and gravel, and the river inside rises quickly in rain.

What you actually see today. The valley is a walker's place rather than a viewing point. Three hut areas serve it: Skagfjörðsskáli in Langidalur, run by the Iceland Touring Association; Básar in Goðaland across the Krossá; and Húsadalur, with huts, a campsite and a small restaurant. From any of them, half-day routes climb to viewpoints — Valahnúkur, at 458 metres, is the standard hour-and-a-half loop and gives the full panorama of the three ice caps and the braided river. Tindfjöll circle, Réttarfell and the Slyppugil ridges take longer. The ground is a mix of birch scrub, black volcanic sand and moss so fragile that a single boot print stays visible for years, which is why the marked paths matter. The woodland is itself a conservation project: grazing was excluded when the Icelandic Forest Service took the area in hand in the 1920s, and the birch now covering the lower slopes grew back from remnants that sheep had kept cropped for centuries.

The two great trails. Þórsmörk is the hinge of Iceland's best-known hiking. The Laugavegur trail arrives here after 55 kilometres from Landmannalaugar, normally walked over four days with hut nights at Hrafntinnusker, Álftavatn and Emstrur. From Þórsmörk the Fimmvörðuháls route continues 25 kilometres south over the 1,000-metre pass between Eyjafjallajökull and Mýrdalsjökull, passing the craters Magni and Móði that were born in the March 2010 eruption and still radiate heat, before descending the Skógá river past a chain of waterfalls to Skógafoss. Walking both back to back is the classic Icelandic long weekend, and the pass is exposed enough that people get into trouble on it every summer.

Getting there and timing. The bus season generally runs from mid-June to mid-September, occasionally longer, and outside it the valley is effectively closed to casual visitors, though winter super-jeep tours do run. Huts must be booked well in advance for July and August. There is no shop, no fuel and no reliable mobile coverage in parts of the valley, so supplies come in with the walker. Weather can turn from still sunshine to horizontal rain within an hour, and the rivers respond immediately. Anyone crossing the Krossá on foot should use the seasonal footbridges rather than wading, and treat the day's conditions rather than the schedule as the deciding factor.