There is a quick way to Oeschinensee, and a long one. The quick way is a gondola and twenty minutes. The long way is most of a day.
We took the long one. Up through the forest, out onto the high traverse, then down to the water from above, the way you earn a lake rather than arrive at one.
By the time we reached it the day-trippers had gone. The surface was flat, and the colour didn't look real.
We didn't swim. We just sat, and let the walk catch up with us.