The Gliwice Canal connects Upper Silesian industrial cities with the Oder. This waterway is a little over 40 km long, and on average about 3.5 m deep. The difference in height in water levels between between the ports in Gliwice and Koźle is 44 m. The construction of the canal started in 1934 and was completed in 1939. The Gliwice Canal was then the most modern waterway in Europe. Today, it plays an increasingly important role as a tourist attraction.