On the road to the Julier Pass, Lake Marmorera is an artificial lake which is part of the Ela Park, the largest nature park in Switzerland.
The lake was formed after the completion of the Marmorera dam in 1954. The former village of Marmorera was submerged and rebuilt over the lake, but many inhabitants preferred to settle in other villages, for sentimental and economic reasons.
There are unfortunately few view points from where to admire the lake, which banks are steep. Stop by the dam to the north if you want to walk around a bit.
Useful links
Swiss Canton of
Graubünden (iSwitzerland Guide) -
Wikipedia