Båven is a lake in the municipalities of Flen, Gnesta, and Nyköping in Södermanland, Sweden. The lake is characterized by branches and many islands, with over 500 km of shoreline. Around Båven there are a number of estates and manors, including Sparreholm, Vibyholm and Rockelstad.
The lake has relatively clean water and a rich bird life with many bird protection areas. The lake is one of the few lakes or waterways in Sweden with the presence of wels catfish.
