In summer months, the park Flussbad Oberer Letten is an anti-urban oasis along the riverfront. Bohemians, bankers, athletes and young mothers all go there to unwind, swim and play volleyball.
Great spot to lie in the summer, swim, drink a beer and people watch. If you're feeling brave jump off the bridge into the river, it's a pretty high drop so not for the faint of heart.
THE hipster place in Zurich! If you're not working out, don't have a tattoo and didn't work on your tan recently, try to avoid it. Otherwise the location and the Limmat are definitely worth it.