In the location's words:

The Große Wukensee, hidden in the north-east of Berlin, is considered by some to be the most beautiful lake in Brandenburg. With its clear waters, it is ideal for swimming, boating and simply hanging out on the shore. The surrounding forest paths are perfect for relaxing walks or a bike ride. Pack a snack and enjoy the day at this cool spot in nature, far away from the hustle and bustle of the city.