Swimming

they have a name for that these days, its 'wild swimming' (i.e what everyone used to do before H&S came along) lots of nice books on it now.
probably been said before but riding up to hampstead ponds in summer, belting out a few circles, then sliding back down the hill has to be one of the best London experiences going.
I really want to check out some exotic places like Droitwich spa this summer.

me too man. i can't wait to get a wetsuit and get up to the ponds.