Lake Saimaa is the largest lake in Finland by surface area at 4400 km2. It is also the fourth largest lake in Europe. It discharges into Lake Ladoga through the River Vuoksi. Saimaa is made up of several different basins connected by narrow straits. It has a very long shoreline as a result of it being a maze of islands, capes, bays and long and narrow inlets. The Saimaa Canal is used to transport goods to Lake Ladoga and from there to the Neva River and the Gulf of Finland. The Soviet Union leased the Soviet part of the canal to Finland for 50 years in 1963. A 50 year extension of the lease is in effect. Russian laws are in force at the canal except for the employment of the Finnish staff operating the canal.
Three provincial capitals in Southeastern Finland are located on the shores of Lake Saimaa: Lappeenranta (South Karelia), Mikkeli (Southern Savonia) and Joensuu (North Karelia). The three towns are not very large, each having about 50,000 inhabitants. There is a major university campus in Joensuu that is part of the University of Eastern Finland. There is a University of Technology in Lappeenranta.