The Peipus Sea (Estonian Peipsi-Pihkva järv, Russian Псковско-Чудское озеро or Чудско-Псковское озеро, Pskowsko-Chudskoe osero or Chudsko-Pskovskoye osero, "Pskov-and-Tschuden-See") is an inland waterway located between Estonia and Russia. At 3,555 km², it is about seven times the size of Lake Constance and ranks fifth among the largest lakes in Europe - after the Ladoga and Onega lakes in Russia, as well as the Swedish Vänern and the Finnish Saimaa.
Wikipedia