#Switzerland, Blausee
A small lake in Switzerland, in the Kander Valley, above the Underground, at an altitude of 887 meters, near the Kander River. The secret of the surprisingly piercing emerald-blue color is the underground springs that feed the lake with crystal water all year round. The huge boulders in the lake and in the park itself were brought by an ancient glacier.
You recognized him, of course. Recently, there was a post about this lake: