The river flows below, the train speeds by above, Zurich’s skyscrapers in the distance: Unterer Letten is the oldest river swimming pool in the city, but it fits seamlessly into its industrial surroundings. You can swim in the strong current because a grate demarcates the end of the pool. Motto: hit the grate partitions feet-first! Tip: Every Tuesday evening the bar under the arcades opens, attracting hipsters from the entire city.