If you wanna go to a small lake surrounded by nature and very close to Zurich, this might be a secret tip.
How to get there: Park on these coordinates: 47.3931664, 8.3758511. From here you have an easy 30min walk to Egelsee, a small nature preserve. In Summer its a great place for swimming and a BBQ. in Autumn you have the perfect mood and the place is empty. Perfect for a small break from the city.