Judging from the parks, Berliners old and young enjoy play. In addition to the trampolines, you can find slides, swings, ping pong tables, seemingly hand-carved creatures for children to climb. Many parks have walls available for painting graffiti. If you get hungry after your play you can often find a cafe or food kiosks inside the park.
Berlin has playgrounds everywhere. I see them in pockets of land between buildings, on empty corners, in parks and public squares. There are ping pong tables in parking spaces and strips of unused road. There are also skate parks, soccer fields, climbing walls, swings, pathways for rollerblades, running and kiteboards. And one rollercoaster.
Within the city of Berlin, there are over 80 lakes, two rivers, and three canals. Depending on where you are and the time of year you can swim, skate, sail, cruise, paddle, bird watch, walk, bike ride, drink coffee or beer, or just put down a blanket and hang out with friends or sit and read.