Seven Island Lake Nature Reserve

Seven Island Lake Nature Reserve () is a nature reserve established in 1956 around Oświn Lake in north-eastern Poland, close to the border with the Kaliningrad Oblast of Russia. 
Geography.
The reserve is located within Warmian-Masurian Voivodeship, in Gmina Węgorzewo of Węgorzewo County.
The area is an important breeding ground for water birds, and is both a Natura 2000 EU Special Protection Area, and a Ramsar site − one of 13 such sites in Poland. 
The reserve covers an area of approximately , consisting of about 3.5 km² of water bodies, 6 km² of marshland and 0.5 km² of forest.