Aletsch Glacier

The Aletsch Glacier (German: Aletschgletscher [ˈaːlɛtʃˌɡlɛtʃər] ^ⓘ) or Great Aletsch Glacier (Grosser Aletschgletscher) is the largest glacier in the Alps. It has a length of about 23 km (14 mi) (2014), a volume of 15.4 km³ (3.7 cu mi) (2011), and covers about 81.7 km² (31.5 square miles) (2011) in the eastern Bernese Alps in the Swiss canton of Valais. The Aletsch Glacier is composed of four smaller glaciers converging at Konkordiaplatz, where its thickness was measured to reach a maximum of 905 metres (2,969 ft). It then continues towards the Rhône valley before giving birth to the Massa. The Aletsch Glacier is – like most glaciers in the world today – a retreating glacier. As of 2016, since 1980 it lost 1.3 kilometres (0.81 mi) of its length, since 1870 3.2 kilometres (2.0 mi), and lost also more than 300 metres (980 ft) of its thickness.

The whole area, including other glaciers is part of the Jungfrau-Aletsch Protected Area, which was declared a UNESCO World Heritage Site in 2001.

The Aletsch Glacier is one of the many glaciers located between the cantons of Bern and Valais on the Bernese Alps located east of the Gemmi Pass. The whole area is considered to be the largest glaciated area in western Eurasia. The Fiescher and Aar Glaciers lying on the east have similar extensions.

Except the Finsteraarhorn, all the highest summits of the Bernese Alps are located within the drainage basin of the glacier. The Jungfrau and Mönch constitute the northern boundary; the Gross Fiescherhorn and Gross Wannenhorn lie on its east side; finally the culminating point, the Aletschhorn (4,193 m (13,757 ft)) is located on the west side.

Before reaching the maximum flow, four smaller glaciers converge at Konkordiaplatz:

South of Konkordiaplatz, the glacier runs towards the valley of the Oberwallis (Upper Valais); on the east side, near Bettmeralp, lies a small glacier lake, Märjelensee (2,301 m (7,549 feet)); from the western side used to enter the Mittelaletschgletscher, but since the end of the 20th century the connection with the Aletsch Glacier has been lost. Further down, until about 1880, the Oberaletschgletscher did also enter the Aletsch Glacier at its mouth. But since then both glaciers have been retreating so far that they do not connect anymore (the Upper Aletsch Glacier did retreat about 1.3 km (0.81 mi) from its connecting point with the Aletsch Glacier), but both serve now only as the source of the river Massa. The river flows through the Lake Gibidum (a reservoir, and coincidentally representing the glacier's mouth region in the 19th century, which is a retreat of more than 4 km (2.5 mi)) and a gorge of the same name before reaching the Rhône near Brig.

The area of the Aletsch Glacier and some surrounding valleys is on the UNESCO World Heritage list, thus it is protected and the facilities are mostly restricted to the external zones. The region between Belalp, Riederalp and Bettmeralp (which is called Aletsch Region) in Valais gives access to the lower part of the glacier. The Bettmerhorn and Eggishorn are popular view points and are accessible by cable car. The Massa river can be crossed since 2008 by a suspension bridge, thus allowing hikes between the left and the right part of the glacier.

The Jungfraujoch railway station (3,450 m) gives a direct access to the upper Aletsch Glacier as well as the normal route to the Jungfrau. It can be reached only from Interlaken in the canton Bern. Hiking paths pass the Konkordia Hut or the Hollandia Hut, eventually reaching other glaciers in the massif.