Coloured lantern slide of a view over Lake Grimsel. Grimselsee or Lake Grimsel is an artificial lake near Grimsel Pass in the Canton of Berne, Switzerland. The dam was completed in 1932. With a volume of 95 mio m?? it is larger than other hydroelectric reservoirs in the region. The Grimsel Hospiz is a former defiant miner's home, and now acts as a 4 star hotel.. Slide number 24 of Box 181 entitled 'Swiss No.1'.