Fimmvörðuháls

The Fimmvörðuháls trail is Iceland's most famous day hike — 25 km from the great Skógafoss waterfall on the south coast, up the Skógá River past more than 20 cascades, across a 1,000 m high pass between two glaciers, and down into the green valley of Þórsmörk. The pass crosses the small saddle between the Eyjafjallajökull and Mýrdalsjökull ice caps; Eyjafjallajökull is the volcano that erupted in 2010, scrambled European air travel for a week, and left two fresh craters (Magni and Móði) and a still-cooling lava field directly on the trail.

The hike is conventionally walked south-to-north from Skógar to Þórsmörk. The first 8 km follow the Skógá River through a wonderland of waterfalls — by some counts more than 25 — with the river-side path easy and constantly photogenic. After the falls, the trail climbs to a high black-sand plateau and the Baldvinsskáli hut (an emergency-stop summer refuge), then traverses a series of ridges to the Fimmvörðuháls pass. From there it crosses the 2010 lava field — black, ropey, and only a decade or so old — past the Magni and Móði craters, and drops 1,000 m through the Heiðarhorn ridge and the Cat's Spine ridge to the Þórsmörk valley floor. Most hikers finish at Básar or Langidalur, where there are huts, bus services to Reykjavík, and the trailhead for the Laugavegur Trail extension.

The trail is open mid-June to mid-September. Outside that window the pass is snowbound, weather risk is real, and rescues happen most years for groups caught by unexpected storms. There's no permit, no fee, and no guide required, but the route is unmarked between the river and the pass — GPS is strongly advised. The Þórsmörk bus runs once or twice daily in season and must be booked ahead; missing it means another night in the valley. Many hikers do the Fimmvörðuháls as the first or last day of the Laugavegur, which extends from Þórsmörk 55 km further north to Landmannalaugar.