Lake Segozero (Russian: Сегозеро, Finnish: Seesjärvi) is a large freshwater lake in the Republic of Karelia, northwestern part of Russia. It is located at 63°18′N 33°45′E / 63.3°N 33.75°E. The Segezha is a major outflow from Segozero and it empties to Vygozero. After the hydroelectric power plant was built on Segezha River the surface area of Segozero have risen from 815 km² to 906 km².