The Aletsch Glacier, around 23 kilometres long and nearly 80 square kilometres in area, is the largest glacier in the Alps. It is part of the UNESCO World Heritage Swiss Alps Jungfrau-Aletsch and stands as an extraordinary natural monument – a remnant of the Ice Age that is visibly receding. The glacier's tongue ends at the Märjelensee, whose turquoise waters meet the ice directly.

The glacier is most easily enjoyed from the viewpoints of the Eggishorn, Bettmerhorn and Moosfluh, reached by mountain railways from Fiesch and Bettmeralp. The Aletsch Panorama Trail runs along the glacier's edge with views across the ice surface and surrounding peaks. A visit to the Aletschwald – a UNESCO-protected Swiss stone pine forest at the glacier's edge – is also well worth the detour.

The region is accessed from the Rhône Valley: from Fiesch, the Eggishorn cable car ascends to the Eggishorn; from Mörel, a gondola serves Riederalp and Bettmeralp. Both access points are reachable by train from Brig. The car-free alps have no public parking.