
1) Lake of Valais
Found on
https://www.crosswordclues.com/clue/mattmarksee

Mattmarksee is a reservoir in the Saas Valley of the Canton of Valais, Switzerland. The Mattmark dam was built from 1960-1965. The lake`s surface area is 1.76 km². The lake lies at a height of 2,197 metres above sea level, between the massifs of the Rimpfischhorn and Stellihorn. The highest peak visible from the lake is the Strahlhorn (4,190 m).....
Found on
http://en.wikipedia.org/wiki/Mattmarksee
No exact match found.