Alpse is one of the most beautiful Alpine lakes in Switzerland, located at an altitude of 1143.2 meters above sea level, covering an area of 13.6 hectares, and can be reached on foot (for 50 minutes), by train or cable car. In July of 2009 and 2010 AD, the color of this lake turned red, due to the high density caused by the algae "Tovellia sanguinea", which abounds in cold water lakes located at an altitude of more than 1000 meters.