Everyone takes tourist boat tours but berlin has regular ferry system that's way cheaper and just as scenic. F10 ferry wannsee to kladow runs every 20 minutes, costs same as bus ticket

Best route is f24 tegelort to alt-tegel - goes through beautiful forested areas past sailing clubs. Takes 30 minutes, feels like countryside not major city

All ferries accept regular bvg tickets so day pass works. Much more peaceful than crowded spree tour boats and you get to cross water instead of just floating down it