Something I've noticed a lot, is just how child and family friendly Berlin is. Berlin has plenty of parks, fields and natural areas and almost all of them have playgrounds for children/young adults. Some of the larger parks even have little mini-zoos with a few animals that can be observed and even fed. There are skates parks, bike parks, tennis courts, mini and full sized football (soccer) fields as well as areas set aside for playing a variety of different activities. Along the canal, there are lots of little courts where they play a game called "Ball" (I'm not exactly sure what it is, but it looks like a great excuse to get together with friends and drink a few beers outside). There are basketball courts, volleyball nets (complete with sand) and in every park, and even in a few unexpected places like street corners and bridges, there are a few stone table tennis tables. Although I haven't noticed any baseball diamonds, there are certainly enough parks that have the capacity to accommodate a game or two.
The residents of Berlin enjoy being active. Even when the weather is horrible, it is not uncommon to find people outside taking advantage of the parks and play areas. These areas even have their own unique cultures. Some areas are local hangouts, some are social gathering places for young singles, some are family friendly and some are more relaxed for those who want to smell the roses (There are flowers everywhere). When visiting Berlin, don't forget to bring a ping pong ball and a paddle... It's a great way to meet a few friendly folks and spend a little quality time outside.