The Aletsch Glacier is the largest glacier in the Alps, running for more than 20 km through the Jungfrau-Aletsch region. Its size is easiest to understand from the ridges above Fiesch, where the ice stream curves below Eggishorn and stretches deep into the mountains.
Most visitors see it from viewpoints or hiking trails rather than by walking on the glacier itself. Clear weather matters: when the clouds lift, this is one of the great alpine views in Switzerland.