Gorner Glacier, Valley glacier in Valais, Switzerland

Gorner Glacier is a valley glacier on the west side of the Monte Rosa massif near Zermatt in Valais, Switzerland. It is about 12.4 km long and 1 to 1.5 km wide, and its glacial system covers 53 km², making it the second largest in the Alps after the Aletsch system. Its lower tongue is covered with debris from numerous medial moraines, and the ice is notable for its bright white colour and blue surface lakes.

Its last high stand came in 1859, after the glacier had advanced 600 metres into cultivated land over 60 years, destroying several alpine huts and some houses. Since then it has lost more than 2,700 metres of length; in 2008 alone it retreated 290 metres, and around 2015 it separated from the Grenzgletscher.

The Gornera, the meltwater stream from the glacier, runs down through Zermatt, where it joins other brooks to form the Matter Vispa. Most of the glacier's water is diverted at a catchment station of the Grande Dixence power plant and ends up in the Lac des Dix reservoir. The glacier and the surrounding peaks are viewed from the Gornergrat at 3,100 m, reached by the Gornergrat Railway from Zermatt.

The best way to see this glacier is by taking the rack railway from Zermatt, which carries visitors to high viewpoints overlooking the ice field. From these elevated spots, you can take in the scale of the landscape without needing to hike across the glacier itself.

The Gornersee at the junction of the Gorner and Grenzgletscher fills each spring and drains within days between June and September, sending up to 150 cubic metres per second down the Gornerbach and briefly lifting the ice by half a metre. Most of the meltwater is captured for the Grande Dixence plant and ends in the Lac des Dix.