The Dümmer See or Dümmer is a large lake in southern Lower Saxony (Germany). It has a surface of 13.5 km² and an average depth of one metre. Its elevation is 37 metres.Dümmer is a popular resort for water sports, but also an important biotope for water birds and located in a zone especially frequented by migratory birds. A large section of its shore is protected by nature reserve areas.