A marsh or marshland castle (German: Sumpfburg) is a type of lowland castle that is situated in marshy or boggy countryside. It uses the natural inaccessibility of the terrain to its defensive advantage.
Examples of well-known marsh castles in Germany include:
- Weferlingen Castle, a ruined castle in Oebisfelde-Weferlingen in the state of Saxony-Anhalt.
- Oebisfelde Castle, the oldest surviving marsh castle in Germany, also situated in Oebisfelde-Weferlingen in Saxony-Anhalt.
- Storkow Castle, in Storkow the state of Brandenburg.
- Calvörde Castle, in Calvörde in the state of Saxony-Anhalt.