The Saimaa lake system has an irregular shape and its individual lakes are kept apart by a great number of islands and isles. Rocks and vast forests are situated on the lake coast. The biggest island is Sääminginsalo and it separates the Pihlajavesi, Haukivesi and Puruvesi lakes. The Saimaa lake is an important junction of waterways. The Vuoksi river flows from the lake, from which several artificial canals were constructed. The Saimaa waterway, which connects the lake with the Bay of Vyborg, is the most important canal. The Saimaa Ringed Seal lives in the northern part of the lake.