The Augustów Canal is a summit level canal which links the Biebrza River in northeastern Poland with the Neman River in Belarus. At over 100 km long, it comprises 18 locks(example pictured) and 22 sluice gates. Ever since the canal was built in 1823−1839 to provide a navigable waterway from the "Congress" Kingdom of Poland to the Baltic Sea bypassing Prussia, it has been described by experts as a technological marvel. It uses a post-glacial channel depression, forming the chain of Augustów Lakes, and the river valleys of the Biebrza, Netta, Czarna Hańcza, and Neman, which made it possible to perfectly integrate the canal with the surrounding elements of the natural environment. Although the project was never finalized, the completed part of the Augustów Canal remained an inland waterway of local significance used for commercial shipping to and from the Vistula and Neman Rivers until rendered obsolete by the regional railway network.