Alster basin

The Alster () is a right tributary of the Elbe river in Northern Germany. It has its source near Henstedt-Ulzburg, Schleswig-Holstein, flows somewhat southwards through much of the Free and Hanseatic City of Hamburg and joins the Elbe in central Hamburg.

thumbnail|Nikolaifleet Nikolaifleet is a canal in the Altstadt of Hamburg, which was the original branch of the Alster estuary. It separates the Cremon island from the mainland. First mentioned in 1188, the Nikolaifleet is considered one of the oldest parts of the Port of Hamburg.

lake in Hamburg

thumb|Isebekkanal in 2005 thumb|Inner city canals of Hamburg Isebekkanal () is a canal in Hamburg, Germany. It has a length of about 3 km and is a remnant of the former stream of Isebek. The small Ottersbek stream flows into it. The Isebekkanal flows into the Alster.