Your next stop should be at the sea (Wannsee). There are many green areas where you can picnic while looking at the water and boats. During the summer season, a small bistro is also open. And if you have kids, there also is a playground.

The second part of the trip is to follow the Treptowkanal back to Berlin. You will take a very nice protected bike road, following a very picturesque route in the woods. Except for a small paved section, the high majority of the route is extremely nice to bike on and well taken care of. Treptow Canal will bring you back to the city, following the water: beautiful, safe and well maintained as well. On the way, you will also find a playground, as well as a few convenience stores when you have to switch sides of the canal. The entire way is very well indicated and you can't get lost.

Finally, to go back to the city center, cycle through the Prellerweg, another great protected path, where no car is allowed. You can stop at the beer garden just before, for your last break of the trip. One of the great advantages about this route is that there are many opportunities to take a break, and if the full itinerary is too much for you, there are S-Bahn stations all the way.