There are three ponds on Hampstead Heath, the mixed pond and, near the Highgate side, the Men’s and Women’s ponds. They’re unfiltered and can be fairly murky and cold but are perfect for a refreshing lunchtime swim on a sunny day. The mixed pond is a busy riot on weekends while the men’s pond is an interesting mix of fitness fanatics, outdoor swimming enthusiasts, gay men and strict Muslim and Jewish men who go there for the single sex bathing. Everyone gets along quite well, all watched over by the slightly bored lifeguard.
There’s a ticket machine by the ponds with a suggested £2 payment but many people don’t give anything as historically the ponds have been free. The Corporation of London (which gained control of the ponds when the GLC was disbanded) have tried to close them down. After local pressure they instead set up the ticket machines to help pay for the lifeguards and maintenance.
Link: Hampstead Ponds