Laugavegur Trail

One of the world's most otherworldly treks, crossing a landscape that shifts by the hour — steaming geothermal fields, rhyolite mountains striped in red and yellow, black volcanic desert, and glacier-fed rivers that have to be waded on foot. Huts along the route mean no need to carry a tent, but the weather is unpredictable even in summer, and the terrain changes character almost every few kilometers.