Finnish lakes are shallow. The average depth of Finnish lakes is six meters, and even the deepest points of Finnish lakes are only a hundred meters deep. Because the Finnish lakes are shallow, they contain a relatively small amount of water. In fact, all the water contained in Finnish lakes could easily fit inside the Russian Lake Ladoga. 

Because Finnish lakes contain a relatively small amount of water, the lakes must be protected. The small amount of water is in danger of becoming polluted, and shallow lakes can suffer from the lack of oxygen during the winter months. 

During the summer, Finnish lakes are full of life. They are home to various species of fish and other, smaller organisms. They are an important food source for many birds and mammals.