The Grande Dixence, the world's highest gravity dam, collects the meltwater of 35 Valaisian glaciers in the region surrounding Zermatt and leading up to Val d’Hérens. Grande Dixence, built in the years from 1951 to 1965, is a construction of incredible magnitude. The large reservoir holds 400 million cubic meters of water, which is channeled into the lake through 100 kilometers of tunnels. The dam withholds Lac des Dix (Lake Dix), its reservoir. With a surface area of 4 km², it is the second largest lake in Valais and the largest lake above 2,000 m in the Alps.
An aerial cable car takes visitors to the top of the dam, which has a magnificent panoramic view of the Valaisian mountains. A variety of mountain hikes begin here, such as the high altitude Ibex Trail.
Guided tours with slide shows and films take place in the interior of the dam.