Lago Greifen

In the vicinity of Lake Greifen, (Greifensee) the famous "Greifensee-Lauf" (a half marathon) is held every year. Greifensee is popular for biking, walking and rollerblading as there's a paved path around the lake. The lake and its surroundings are under UNESCO protection and building isn't allowed, resulting in fantastic reeds and rich fauna and flora (about 400 species of plants are in the lake and 19 in its tributaries). Nature reserves are important for birds to breed, including more than 120 migratory species.