Märjelen Reservoir

The Märjelensee, or Märjelen Lake, lies on the edge of the Great Aletsch Glacier at about 2,300 metres, a short walk from the Eggishorn above Fiesch in the Valais. The location often causes confusion, because this guide lists it under Binn; in fact it belongs to the Aletsch Arena and is reached from the Fiesch and Fiescheralp side, not from the Binn valley or from Gletsch, which lie elsewhere. The setting is unusually dramatic: the lake sits in a hollow right next to the glacier's flank, with ice, rock and sky filling the view.

The Märjelensee has an interesting history. In earlier centuries it was a large ice-dammed lake, held back by the mass of the Aletsch Glacier, and it grew and shrank as the ice advanced and retreated. When the barrier gave way, the water could drain suddenly beneath the ice, and the outflow was a hazard for the valley below. Over time the lake was reduced and the water was managed, and as the glacier has thinned in recent decades, the lake has become much smaller than it once was. Today only a modest sheet of water remains, together with small ponds, and its shrinkage has become an easily visible sign of climate change in the Alps.

Its position still makes it a lovely goal for a walk. From Fiescheralp or the Eggishorn, paths lead across alpine pasture and rocky slopes to the lake, with growing views of the Aletsch ice stream, the longest in the Alps. The terrain is not technical, and the walk is suitable for families and fit older walkers, though the altitude can be tiring and the weather can change quickly. A mountain restaurant, the Gletscherstube, stands close to the lake and offers a place to rest with a view of the ice.

The area is within the UNESCO Swiss Alps Jungfrau-Aletsch zone, so visitors are asked to stay on marked paths and to respect the fragile environment. The best season is summer and early autumn, when the paths are free of snow and the huts are open. Bring layers, sun protection and sturdy footwear, because the high-mountain sun and wind are strong.

Combine the walk with a visit to the Eggishorn viewpoint, which has its own entry, for a full day in one of the most impressive landscapes of the Swiss Alps.