If you feel like a paddle on the water, hire a boat for an hour or two and go boating on the Serpentine in Hyde Park. If faster water sports are your style, Docklands has jetskiing, waterskiing and windsurfing. London's parks - especially Hyde Park and Regents Park - are delightful for walking. There are also bike-hire joints all over the city for cyclists, although if you're planning to ride in traffic you might be taking your life in your hands. You can even hire a gee-gee and go horse riding if you're keen for a canter. And of course, London is littered with gyms, sports centres and even climbing walls. North of the centre, Highgate Ponds on Hampstead Heath offer open-air swimming all year round.