One of Zurich's many 'badis' (lidos, would be the nearest, in English). Probably the best for families within Zurich City. Many life guards, sandy beach, children's outdoor pool, excellent restaurant. Remains open in the water (albeit with showers and changing rooms closed) so also good for quiet, winter swimming. Several events, like an annual lake crossing, start from there, in addition to some competitions like the Ironman.