Weissmies, Mountain summit in Valais, Switzerland.

Weissmies is a mountain summit in the Pennine Alps of Switzerland, sitting on the ridge that separates the Saas valley from the Zwischbergen valley. Three glaciers cover its northeast, southeast, and west faces, shaping the terrain that climbers cross on their way to the top.

Jakob Christian Häusser and Peter Josef Zurbriggen made the first ascent in 1855 via the Triftgrat. Local guides doubted the peak could be climbed without them; after following the pair's footprints to the summit, they found the highest point had indeed been reached. The east face was climbed in 1876 by J. A. Peebles, E. P. Jackson and Margaret Jackson with guides P. Schlegel, U. Rubi and J. Martin.

The name Weissmies comes from the local Valais dialect and points to the white, moss-like snow that covers the upper slopes year-round. Anyone who reaches the higher sections of the mountain can see why the name stuck, as the pale, snow-covered rock stands out against the surrounding peaks.

Most climbers start from the top station of the Hohsaas cableway, which sits at around 10,170 ft (3,100 m) and serves as the base for the northwest route. Glacier travel and solid mountaineering experience are needed, as the upper sections involve crevassed ice and exposed ridges.

The Weissmies is the easternmost four-thousander of the Pennine Alps, standing between the Lagginjoch (3,500 m) to the north and the Zwischbergen Pass (3,260 m) to the south. Its massif also holds the Lagginhorn and Fletschhorn, two nearly equal summits just to the north.