The Finnish Lakeland is located in the southeast of Finland; but small parts extend even as far as Russia. The area has no distinctive geomorphological limits, but is generally regarded as the catchment area of the rivers Kokemäenjoki, Kymi and Vuoksi.
The basin of the Finnish Lake District were gouged by the glaciers during the Weichselian. After the retreat of the ice itself Moränenmulden, glacier basins and old sinks and tectonic trenches with melt water, most of which were still connected to the Ancylus Lake, a huge meltwater at the site of today's Baltic crowded. As a result of postglacial land uplift of these basins were separated from this meltwater in the course of thousands of years more and more. The emergence of Salpausselkä moraines in the south of the region and of the Suomenselkä in the northeast accumulated large amounts of melt water and rainwater in eastern Finland that was formed still more than 400 km long lake from today Iisalmi in the north to Salpausselkä 6,000 years ago. Respectively only by the breakthrough of the Kymi River and rivers Vuoksi before 6000. 5,000 years found the lake system a natural drainage, so that lowered the water level and the current topography began to emerge. The land uplift is an ongoing process to date, which can be silt concluding Seearmen about within a generation, so that a new lake is created.
The moor and woodlands, lakes plate with well over 100,000 km ², the largest lake district in Europe.
The number of lakes in the Finnish Lake District varies with the definition of a lake. According to the official Finnish count that a body of standing inland waters with a size conceives ≥ 0.05 acres with a lake, the number of lakes in the region of 42,200. Many lakes are dissected by water Engen in numerous bays, basins and branches of the lake, which in turn are often regarded as separate lakes. The biggest and greatest branched lake is approximately 4370 km ², the Saimaa lake system.
The lakes of the region are mostly quite shallow, the deepest and most water by volume is at a maximum depth of 95 m Päijänne.
The largest lakes are connected by rivers, straits and artificial water channels together so that the Lakeland plays a significant role for the inland waterways. The waterway between Lappeenranta in the south and in the north Varkaus the Lake District is about 230 km long and continuous course without canals and locks at a level of about 76 m.