Laugavegur + Fimmvörðuháls (to Skógar)

Straight out of Landmannalaugar the trail climbs hard through the multicoloured rhyolite and the Laugahraun lava field onto the highland plateau — the steepest sustained climbing of the whole route, past steaming fumaroles near Hrafntinnusker. Snow patches linger here well into summer even in dry years, and low cloud can close visibility to almost nothing with little warning. Past the Hrafntinnusker hut the ground begins its long unwind toward Álftavatn, dropping through the first of several snow-filled ravines. No settlements, no shelter beyond the hut itself, and the most weather-exposed few hours of the whole trek.

Logistics: Hrafntinnusker hut (around km12) is the only shelter on this stretch and gets booked out months ahead for summer — arrange it, or a camping spot there, well in advance rather than assuming a bed or pitch on the day.

Navigation: Route-marked with posts across open ground, but in fog or driving rain near Hrafntinnusker the posts can be hard to pick out at distance — this is the stretch where parties most often lose the line.

The long middle of the trek and its biggest combined stretch of climbing and descending. The ravines below Hrafntinnusker give way to greener, more sheltered ground around Álftavatn, then the trail opens onto the black sand desert of Mælifellssandur — flat, exposed and unpleasant in wind, with several unbridged streams to wade through the Álftavatn–Emstrur stretch. Beyond Emstrur the ground drops into birch scrub and canyon country toward Þórsmörk, crossed by the Þröngá, usually the coldest and deepest ford of the trip. From Þórsmörk the trail turns straight back uphill onto Fimmvörðuháls, a second big climb inside the same long stretch.

Logistics: The Þröngá crossing just before Þórsmörk is usually the deepest and coldest wade of the whole route — river levels rise fast after rain, so check conditions and cross where the markers indicate rather than the most obvious-looking line.

Navigation: Marker posts across Mælifellssandur are spaced wide apart in featureless terrain — in poor visibility it's easier to wander off line here than anywhere else on the sand. River crossing points are marked but shift slightly year to year as channels move.

The last climb up to Baldvinsskáli hut passes close beneath Eyjafjallajökull and Mýrdalsjökull, crossing the Goðahraun lava field formed in the 2010 eruption past the twin craters Magni and Móði — the ground between the glaciers has the least predictable weather on the whole route, with fog and snow possible even in July. A memorial cairn near the pass marks hikers lost here in 1970. From Baldvinsskáli the trail turns almost entirely downhill: a long, relentless descent alongside the Skógá river past a continuous run of waterfalls into Skógar, hard on the knees rather than the lungs and the single biggest descent of the whole trek.

Logistics: The col between the glaciers is the most weather-unstable ground on the entire route — check the forecast immediately beforehand and be ready to shelter at Baldvinsskáli rather than push on if it closes in.

Navigation: Waymarked with posts across the pass, but they're easy to lose in the fog that regularly sits on this col — this is the one place on the whole trek worth turning back from rather than pressing on blind.