This is absolutely.
The lake was once famous because it used to become red in summer, due to a kind of algae living in the lake. During the past years, the amount of al algae in the water had been decreasing and since the 1964 the red color disappeared. Inside the park info point, close to the lake, there is an exhibit about the "SALTO" project: a study about the possible reasons that could stopped the lake from becoming red in summer, you'll be surprised to find out in how many ways humans had been able to cause damages to the lake.
Today, the access to the lake by car is strictly regulated. There are some toll car parking, we suggest you to leave there the car and take the bus, find more info at http://www.pnab.it/vivere-il-parco/come-muoversi/con-la-mobilita-del-parco/mobilita-val-di-tovel.html (italian language) or www.pnab.it/en.html. The lake is close to the Tuenno village, it is the biggest natural lake of the Trentino region and although it doesn't become red anymore, the water is incredibly transparent, the color is , the mountains and the sky .
A shortis absolutely mandatory to look inside the crystal water. Along the path, there are the park info point, a bar and two hotels