Mittelaletsch Glacier, Glacier in the Bernese Alps, Valais, Switzerland

The Mittelaletsch Glacier is a valley glacier in the Bernese Alps, entirely within the canton of Valais. It begins on the east slope of the Aletschhorn (4194 m) and the south slope of the Dreieckhorn (3811 m), and its upper section is steep, with gradients partly above 40%. It flows southeast between the Geisshorn (3740 m) and the Olmenhorn (3314 m); in 2011 its length was given as 5.33 km.

The Mittelaletsch Glacier was a side glacier of the Grosser Aletsch Glacier and remained connected to it by continuous ice until 1970. In December 2001 its area, together with the Grosser Aletsch, was inscribed as part of the UNESCO World Natural Heritage Swiss Alps Jungfrau-Aletsch.

The glacier lies entirely in the canton of Valais and belongs to the system of the Grosser Aletsch Glacier, whose meltwater it feeds about one kilometre away; in summer a small meltwater lake sometimes forms at its edge. Since December 2001 its area has been part of the UNESCO World Natural Heritage Swiss Alps Jungfrau-Aletsch.

The glacier lies in a side valley above the Grosser Aletsch Glacier, and its meltwater flows about one kilometre to join it; in summer a small meltwater lake sometimes forms at the edge. The tongue stood at 2292 m in 1992. Access is on foot only, with no mountain stations on the glacier itself.

The glacier's meltwater flows about one kilometre to the Grosser Aletsch, which absorbs it; in summer a small meltwater lake sometimes backs up along its edge. A 2013 forecast expected a lake to form below the Olmenhorn's first valley step, with a smaller one further back later in the 21st century.