Get a dose of vitamin D at Mythenquai Beach. Once you've worked on your tan, stick around and watch the sky dance with different colors as the sun slowly disappears.
You'll find Mythenquai Beach in the leafy neighborhood of District 2. Entry is free, so you can leave your money tucked away in your pocket. While you're in these parts, why not explore a few other interesting sights, such as Bahnhofstrasse, Zoo Zurich and Swiss National Museum?