Just 15 minutes by bike or half an hour on foot from the S-Bahn stations, Grunewald or Heerstraße is one of Berlin's most picturesque bathing spots. It is the perfect place to clear your head after a day in the city, as I did almost every afternoon while writing my Bachelor's thesis a few summers ago.

After a long day of sightseeing, you can lie down on the fluffy grass and take a dip. The deep waters of the Teufelssee provide the perfect cold refreshment. Just don't swim too far past the little fake island, as the beauty of this spot is also appreciated by the birds and fish that live there.

If you want to see some real German culture, this is your chance, as there is also an FKK beach at this lake. This means that many people sunbathe and swim naked. This is a tradition from the time when East Germany was under Soviet rule. As a sign of protest, people under occupation wanted to express their freedom in another way—by going naked on beaches. You can find some of these around Berlin.