Swim Serpentine ~ London, United Kingdom
Swim Serpentine is an open water swimming event that is staged in the beautiful setting of the famous Serpentine in Hyde Park, the venue for the open water swimming competition at the London 2012 Olympic Games.

This year they have added extra events:

1/2 mile swim (minimum age of 12)
One mile swim (minimum age of 16)
Two mile swim (minimum age of 16)
Super Six swim (minimum age of 18)

The Salvation Army Fundraising Events
101 Newington Causeway London SE1 6BN, United Kingdom