A nice place to wallk in the forest and on the Havel river bank is Pfaueninsel .means Peacock island.
To get there u need to take the S line from Zoologischer Garten tain station to get off in Wansee train station,and to take the bus from there to Pfaueninsel . The place for me is the nicest in Berlin and the most pastoralic.With its small small romantic castle and the peacocks running freely near by. On the hil in the park there is a neutiful church that from there amazeing view on the river and forest,and also a nice wooden russian house from the 19 century,where u can sit on its balcony eat a nice luanch and view the boats in the river.