Aletschhorn, Mountain summit in Valais, Switzerland

The Aletschhorn is a glaciated summit of the Bernese Alps in Valais, reaching 4,194 m and second only to the Finsteraarhorn in that massif. The Aletschfirn lies on its north flank, while the Oberaletsch and Mittelaletsch glaciers descend southwest and southeast from it. Its four sub-peaks include the Kleines Aletschhorn at 3,745 m.

The Aletschhorn was first climbed on 18 June 1859 by Francis Fox Tuckett with guides J. J. Bennen, V. Tairraz and P. Bohren, who had bivouacked in rock holes above the Mittelaletsch Glacier. Tuckett took barometer readings on the summit and, descending the north face, escaped an avalanche before returning via the Mittelaletsch. In 1863 Emma Winkworth became the first woman to reach the top.

The mountain draws climbers from around the world and stands within a UNESCO World Heritage site that reflects the geological and natural importance of the Swiss Alps. The area maintains strong ties to traditional alpine guiding communities that have shaped this landscape for generations.

The usual starting points are the Oberaletschhütten (2,640 m) above Blatten bei Naters and the Mittelaletschbiwak (3,013 m) above Fiesch. The northeast ridge from the biwak is rated PD+ and takes 4–5 hours; the south-east ridge and south-west rib from the Oberaletschhütten are rated AD and take 7–8 hours. The north face, reached from the Hollandiahütte (3,240 m), is the hardest line at S.

The Aletschhorn is considered the coldest mountain in the Alps. Its first climbers, reaching the summit on 18 June 1859, noted the icy temperature and a wind so strong it blew snow and threatened to knock them over. Francis Fox Tuckett carried a barometer and made scientific observations on the summit.