In London, try the Serpentine Lido, a roped-off patch of the artificial lake in the center of Hyde Park. The water looks a tad murky, but the views of the skyline, including the Houses of Parliament, compensate.
Berlin’s suburbs are dotted with lakes. A local favorite: Heiliger See–or Holy Lake–in Potsdam, fed by cool springs. Swimmers can ogle the neoclassical palaces of Prussian kings, as well as the lakeside homes of today’s superrich.
In Bern head for the Marzili baths, right beneath the Parliament building. Or stroll a kilometer upstream and plunge into the River Aare, to be carried back to the city by the fast-paced current.
The cleanup of Copenhagen’s harbor has allowed the opening of a 500-square-meter lagoon in the central port district. Watch the big ships go by as you swim.
One leftover from the Barcelona Olympics of 1992 is the giant swimming pool, now open to the public and handily placed among the museums, galleries and gardens on Montjuic hill.
Denizens of overheated Paris make for the Butte-aux-Cailles pool, where the water, supplied by its own underground source, is so pure that customers carry it away in bottles.
