These are terrain sections, not prescribed walking days. Where one research section covers a long distance, it is split at useful landmarks so you can shorten a day or rebalance the itinerary around it.
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.
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.
In poor weather: The most weather-sensitive ground of the whole trek: high, exposed and prone to sudden fog, wind and even summer snow with very little warning. Conditions here can turn a straightforward walk into a genuinely serious one within the hour.
Escape options: None. Landmannalaugar and Hrafntinnusker hut are the only points of shelter; there is no realistic bail-out partway through the climb.
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.
Around km 18 to greener6 km
greener to black sand desert of Mælifellssandur10 km
black sand desert of Mælifellssandur to Around km 5622 km
Around km 56 to Around km 615 km
1,502 m total ascent across this broader terrain section
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.
In poor weather: River levels across this stretch rise fast after rain or on hot days when glacier melt increases. A crossing that's ankle-deep in the morning can be knee-deep or worse by afternoon. Mælifellssandur has no shelter at all from wind-driven rain.
Escape options: Álftavatn and the Emstrur (Botnar) hut are the only real stopping points; Þórsmörk has road access (highland bus or 4x4 only) and is the last easy exit before the trail commits to the Fimmvörðuháls climb.
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.
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.
In poor weather: Wind and fog on the col between the glaciers routinely run worse than the general forecast for the wider area, the trail's single most weather-sensitive point. The waterfall descent gets slick underfoot in rain.
Escape options: Baldvinsskáli hut is the only shelter on the high section; once the descent to Skógar begins there is no real way off until the bottom.