A swimmer takes a dip in the Serpentine River before the annual Christmas Day Peter Pan Cup handicap race in Hyde Park, London, December 25, 2015. (Photo by Andrew Winning/Reuters)





A swimmer emerges after taking a dip in the Serpentine River before the annual Christmas Day Peter Pan Cup handicap race in Hyde Park, London, December 25, 2015. (Photo by Andrew Winning/Reuters)





Swimmers climb out after taking part in the annual Christmas Day Peter Pan Cup handicap race in the Serpentine River, in Hyde Park, London, December 25, 2015. (Photo by Andrew Winning/Reuters)





Swimmers prepare to take part in the annual Christmas Day Peter Pan Cup handicap race in the Serpentine River, in Hyde Park, London, December 25, 2015. (Photo by Andrew Winning/Reuters)





Swimmers prepare to take part in the annual Christmas Day Peter Pan Cup handicap race in the Serpentine River, in Hyde Park, London, December 25, 2015. (Photo by Andrew Winning/Reuters)





A swimmer takes a dip in the Serpentine River before the annual Christmas Day Peter Pan Cup handicap race in Hyde Park, London, December 25, 2015. (Photo by Andrew Winning/Reuters)





Two Scottish Terriers wear Christmas themed coats as they join their owners to watch the annual Christmas Day Peter Pan Cup handicap swimming race in the Serpentine River, in Hyde Park, London, December 25, 2015. (Photo by Andrew Winning/Reuters)





Swimmers prepare to take part in the annual Christmas Day Peter Pan Cup handicap race in the Serpentine River, in Hyde Park, London, December 25, 2015. (Photo by Andrew Winning/Reuters)





Swimmers cheer as the first participant begins the annual Christmas Day Peter Pan Cup handicap race in the Serpentine River, in Hyde Park, London, December 25, 2015. (Photo by Andrew Winning/Reuters)





Swimmers start in the annual Christmas Day Peter Pan Cup handicap race in the Serpentine River, in Hyde Park, London, December 25, 2015. (Photo by Andrew Winning/Reuters)





Swimmers climb out after taking part in the annual Christmas Day Peter Pan Cup handicap race in the Serpentine River, in Hyde Park, London, December 25, 2015. (Photo by Andrew Winning/Reuters)





Swimmers take part in the annual Christmas Day Peter Pan Cup handicap race in the Serpentine River, in Hyde Park, London, December 25, 2015. (Photo by Andrew Winning/Reuters)