Lake Piva () is a reservoir in Montenegro. It is the largest lake entirely within the country, located in the northwest, in Pluà ¾ine Municipality. The surface of the lake is 12.5 kmò, the length is 45 km, and the maximum depth is 188 m. The elevation is 675 m above sea level.
The artificial lake is the result of the construction of Mratinje Dam on the Piva River. On the bottom of the lake there is the old town Pluà ¾ine; Piva Monastery was also there, but it has been relocated. The new location of the monastery is 8 km from Pluà ¾ine, and 3.5 km away from the original location of the monastery. The relocation has started in 1969 and finished in 1982. The old confluence of the Komarnica into the Piva was submerged as well.