Fedaia Lake () is a reservoir at an elevation of on the Fedaia Pass in the Dolomites, Italy. It lies on the border between Trentino and the Province of Belluno (Veneto), at the foot of the Marmolada, the highest peak in the Dolomites. The name of the pass derives from the Ladin word ' (sheep), as the area was formerly used for grazing.
The reservoir was created by the construction of a dam high, long, and thick at the base. The resulting lake is approximately long. Since 1950 it has been used for hydroelectric power generation, with a capacity of 20 MW, drawing on meltwater from the Marmolada glacier. In 1950 the physicist Antonio Rostagni of the University of Padua established a cosmic ray laboratory at the foot of the dam, which operated until 1955.