Saukko (Pu110) was a small submarine that served in the Finnish Navy during the second World War. It was designed not to exceed 100 tonnes, as it was planned for use in Lake Ladoga, and according to the 1920 Treaty of Tartu, no nation was allowed to use naval ships of more than 100 tonnes on the lake (When completed, Saukko weighed somewhat more than this). The submarine could be divided into separate sections and transported by rail. The conning tower could be lifted off entirely. The engines were in the aft section and the batteries in the forward section. The name "Saukko" means European otter.