What is the largest natural lake in Europe?

The largest natural lake in Europe is Lake Ladoga in northwestern Russia.

Ladoga covers roughly 17,700–18,000 square kilometres, making it larger than Lake Onega, Europe’s second-largest lake. It lies in the Republic of Karelia and Leningrad Oblast, close to Saint Petersburg, and drains westward through the Neva River into the Gulf of Finland. The lake contains about 660 islands, including the Valaam archipelago.

Its basin was shaped by repeated glacial activity, which excavated deep depressions and left a varied shoreline of rocky northern coasts and shallower southern waters. Ladoga is an important freshwater, fishing and transport resource, and its waterways connect with the broader Baltic and Volga systems.

A frequent source of confusion is Lake Baikal. Baikal is far larger and deeper, but it is generally classified as an Asian lake because it lies east of the conventional Europe–Asia boundary within Russia. “Largest in Europe” therefore means Ladoga by surface area; Lake Onega follows it, while Lake Vänern is the largest lake in the European Union.