Süderelbe

The Süderelbe (German: ['zyːdɐˌʔɛlbə] ) (Southern Elbe) is the biggest anabranch of the Unterelbe river in the area which is now the Port of Hamburg, Germany. Its natural flow path was redirected through the Köhlbrand.

Source: Wikipedia https://en.wikipedia.org/wiki/Süderelbe