Get Inspired: Swimmers prepare for Swim Serpentine
BBC London meets some of the 4,5000 swimmers who will be taking part in the inaugural Swim Serpentine on 24-25 September.
Jeremy Joseph, one of those taking part, also reveals some interesting advice he was given for the race.
If you want to find out how to get into all forms of swimming, read our special guide.
Extra footage comes from Episode One of 'The Doctor who gave up Drugs' with Dr Chris Van Tulleken.