Not far from Sydney, in the suburb of Bondi Beach, there is a cold-water swimming club on the bay called the Bondi Icebergs. Every Sunday from May to September, more than 700 swimmers race in order to make, or stay in, the club. To make the club, a swimmer must swim in a race at least three Sundays a month for five years. If they make the club, but then manage to swim only two Sundays in one month, they will be banned from the club for a year.
You can read more about the history of the club on the Bondi Icebergs website. If you go to Sydney during the winter and want for a new sort of active jaunt, it's cheap to try the pool. Adults can swim for $5 and children for $3.50. If you're squeamish about crowds, there are pool cams (only a couple people when I Iooked late Friday night). If you're not quite sure about the water, there's a daily temperature measurement (63 Fahrenheit today). If the cold-water swimming and after-dip drinks aren't enough to draw you in, the website tallies the number of whales seen from the club deck (39 so far).