The Ladoga Lake

Lake Ladoga (Russian: Ладожское озеро (Ladozhskoye Ozero), Finnish: Laatokka) is the largest lake in Europe, located in Karelia and Leningrad Oblast in northwestern Russia, near the border with Finland. The area of the lake is 17,700 kmІ (approximately 6,800 square miles). It has about 660 islands with the total area of 435 kmІ. Most of the islands are situated near the northwestern coast, including the famous Valaam islands. The lake drains into the Gulf of Finland of the Baltic Sea via river Neva. The area of its basin is 276,000 kmІ. The basin of the Ladoga Lake includes about 50,000 lakes and 3,500 rivers longer than 10 km. About 85% of the water income is due to the three most important tributaries:
River Svir from lake Onega (south-east)
River Vuoksi from lake Saimaa in Finland (west);
Volkhov River from lake Ilmen (south).
Ladoga has its own endemic Ringed Seal subspecies.

The lake formed an important part of the Trade Route from the Varangians to the Greeks. The oldest Russian capital, Old Ladoga, took its name from the lake. The ancient Valaam Monastery was founded on the island of Valaam (Finnish: Valamo), the largest in Lake Ladoga, abandoned between 1611–1715, magnificently restored in the 18th century, and evacuated to Finland during the Winter War in 1940. In 1989 the monastic activities in the Valaam were resumed. Other historic cloisters in the vicinity are the Konevets Monastery, which sits on another island, and the Alexander-Svirsky Monastery, which preserves fine samples of medieval Muscovite architecture. Between 1617–1721 the Swedish-Russian border was drawn through Lake Ladoga, then later 1812–1940 the border between Finland and Russia. During the siege of Leningrad, 1941–1944, lake Ladoga provided the only access to the besieged city. Supplies were transported into Leningrad with trucks on winter roads over the ice, the "Road of Life", and by boat in the summer.