Elbląg Canal (; ; ) is a canal in Poland, in Warmian-Masurian Voivodeship, in length, which runs southward from Lake Drużno (connected by the river Elbląg to the Vistula Lagoon), to the river Drwęca and lake Jeziorak. It can accommodate small vessels up to displacement. The difference in water levels approaches , and is overcome using locks and a system of inclined planes between lakes. Today it is used mainly for recreational purposes. It is considered one of the most significant monuments related to the history of technology and was named one of the Seven Wonders of Poland. The canal was also named one of Poland's official national Historic Monuments (Pomnik historii), as designated January 28, 2011. Its listing is maintained by the National Heritage Board of Poland. History The canal was designed between 1825 and 1844 by Georg Steenke, carrying out the commission given by the King of Prussia. Construction began in 1844. The difference in height over a section of the route between the lakes was too great for building traditional locks; an ingenious system of inclined planes based on those used on the Morris Canal was employed instead, though the canal includes a few locks as well. There were originally four inclined planes, with a fifth added later, replacing five wooden locks. Built under the name Oberländischer Kanal (Upland Canal) and situated in the Kingdom of Prussia, it was opened on the 29 October 1860. Since 1945 the canal is now in Poland. After wartime damage was repaired, it was restored to operation in 1948 and is now used for tourism. The canal underwent renovation between 2011 and 2015 and is now again open to navigation. The inclined planes The four original inclined planes are, in order from the summit level downwards, Buczyniec (Buchwalde) with a rise of and a length of , Kąty (Kanthen) with a rise of and a length of , Oleśnica (Schönfeld) with a rise of and a length of , and Jelenie (Hirschfeld) with a rise of and a length of . The fifth incline is Całuny Nowe (Neu-Kussfeld) with a rise of . It was built to replace five wooden locks close to Elbląg. They were constructed from 1860 to 1880. The canal worked independently of other waterways and as a result the boats were designed within the limits of the inclines. The boats had a maximum length of , a