Berlin's largest lake, the Müggelsee, is hemmed in by forest on two sides and hugely popular for swimming and boating on hot summer days. Taking tram 60 from S-Bahn to Friedrichshagen (or walking 1.5km south on historic and cafe-lined Bölschestrasse) gets you to the Müggelpark. Besides restaurants and beer gardens, there's also the landing docks of Reederei Kutzker , which runs one-hour lake tours several times daily from mid-April to mid-October.
For a walk in the woods, head to the other side of the Spree via the nearby Spreetunnel. The closest public lake beach, with boat rental, Seebad Friedrichshagen , is about 300m east of the Müggelpark. On Sundays, there's a flea market at S-Bahn station Friedrichshagen.
