Lake Sils, Lake in Upper Engadine, Grisons, Switzerland

Lake Sils lies at 1,797 metres above sea level between Maloja and Lake Silvaplana, with a surface area of 4.1 km² that makes it the largest lake of the Engadine and the largest natural lake in the Alps above 1,000 metres. It was formed by a prehistoric landslide dam, and the wooded Chastè peninsula extends into the water at its north-eastern end.

A large prehistoric rockslide deposited debris across the valley floor and blocked the natural drainage, forming the lake. That single geological event shaped the wider Upper Engadine valley in a way that is still visible today.

The lake sits between the village of Sils Maria and the Maloja Pass, an area that has drawn painters, writers, and musicians since the 19th century. Many visitors today come simply to walk the shore and watch the light shift across the water at different times of day.

Marked trails run around the shore and connect the village of Sils Maria with the Maloja side, so the lake can be explored from several angles. Weather at this altitude can shift quickly, so layered clothing is worth having even in summer.

The peninsula of Chasté juts into the lake and is almost entirely covered by forest, offering one of the few points where water can be seen on three sides at once. It is reachable on foot and tends to be quieter than the main shoreline paths most visitors follow.