Bandak is a lake in the municipalities of Kviteseid and Tokke in Vestfold og Telemark county, Norway. The lake, which is part of the Telemark Canal route, belongs to the Skien watershed. The river Tokke flows into the lake, and the outlet is via the river Straumane, to Kviteseidvatn. Average depth is 121 meter or about 50 meters below sea level. The lake is 2 km at the widest. The catchment area is 2556 km2.The Tokke Hydroelectric Power Station utilizes the hydraulic head from Lake Vinje to Lake Bandak of ~394 meters to generate electricity. It is one of northern Europe's largest power plants with a production of some 440,000 kilowatts.