I tried to find the name of this valley, but to no avail. So I will describe the location as best as I could. This is the Austrian Tirol and Italy lies just beyond the peaks on the horizon. This photo was taken facing south from Penken peak, altitude 2300mtr. Immediately below is Zillertal valley (unseen in this photo), running from east to west, left to right on the photo. The valley showing in this photo branches off Zillertal at the town of Mayrhofen, which is some 1200 meters below Penken. The small artificial lake is called Speicher Stillup.
And yes, we trekked up 1200 meters from Mayrhofen, and then back down again. It was tough going, but we enjoyed it. The wonderful vista makes it well worth it! Image is best viewed large.
Nikkor 18-70mm G