The Pihlajavesi is a lake south of the town of Savonlinna and is part of the Saimaa lake system. With an area of 712.59 km ², it is the sixth largest lake in Finland and spreads over an area of about 40 km long and 20 km wide.
On the islands in the Pihlajavesi formed over the centuries a unique island culture after Finnish settlers had cultivated the islands. The islanders thought they were safe from attackers, also was a risk that the cattle ran off into the woods or was being torn by predators on the islands is lower than on the mainland. However, many houses were destroyed in a campaign of Russian Cossacks Vilim Fermor in 1743 and killed at least 43 settlers.
Even in 1930 there were in the lake some 20 inhabited islands with a population of around 1,000 people. Due to continuous rural exodus, the number of islanders has declined to less than 200 today.
The labyrinth-like dissected by thousands of islands lakes area is not only the nesting of many species of birds, but also the home of the Saimaa ringed seal. About 60 pieces of this endangered seal species live here.
The Pihlajavesi belongs together with the castle Olavinlinna to the 27 official landscapes in Finland.