Ivankovo Reservoir or Ivankovskoye Reservoir (Russian: Иваньковское водохранилище), informally known as the Moscow Sea, is the uppermost reservoir on the Volga, in Moscow and Tver Oblasts of Russia, located some 130 km north of Moscow. The dam of the reservoir is situated in the town of Dubna. The town of Konakovo is located on its southern coast. The reservoir is connected to the Moskva by the Moscow Canal, and is the principal fresh water source for the city of Moscow. Its area is 327 km2, and the area of its drainage basin is 41,000 km2 .
