Achterwasser

thumb|300px|The Achterwasser off the Loddiner Höft

The Achterwasser (Low German achtern = "rear, behind") is a lagoon forming a bay on the Peenestrom river, which flows into the Baltic Sea. This lagoon extends so far into the island of Usedom, that it is only separated from the Baltic Sea by a narrow barrier spit between Ückeritz and Zinnowitz. It is bordered to the north by the peninsula of Gnitz and to the south by the Lieper Winkel. The reed-lined south-eastern bay is called the Balmer See, and the one to the southwest, which can only be accessed with difficulty on its western shore, is the Krienker See.