LONDON, ENGLAND - SEPTEMBER 24: A swimmer wipes away water from her face as she climbs out of the Serpentine lake after completing the Swim Serpentine course on September 24, 2016 in London, England. The first ever Swim Serpentine, an open water swimming festival, is held today which sees around 4000 competitors swim a one mile course in the Serpentine lake in Hyde Park. (Photo by Jack Taylor/Getty Images)
LONDON, ENGLAND - SEPTEMBER 24: Swimmers prepare before the start of Swim Serpentine on September 24, 2016 in London, England. The first ever Swim Serpentine, an open water swimming festival, is held on Saturday which sees around 4000 competitors swim a one mile course in the Serpentine lake in Hyde Park. (Photo by Jack Taylor/Getty Images)
LONDON, ENGLAND - SEPTEMBER 24: Swimmers take part in Swim Serpentine on September 24, 2016 in London, England. The first ever Swim Serpentine, an open water swimming festival, is held today which sees around 4000 competitors swim a one mile course in the Serpentine lake in Hyde Park. (Photo by Jack Taylor/Getty Images)
LONDON, ENGLAND - SEPTEMBER 24: Swimmers prepare by taking a dip in the water as they take part in Swim Serpentine on September 24, 2016 in London, England. The first ever Swim Serpentine, an open water swimming festival, is held today which sees around 4000 competitors swim a one mile course in the Serpentine lake in Hyde Park. (Photo by Jack Taylor/Getty Images)
LONDON, ENGLAND - SEPTEMBER 24: Swimmers take part in Swim Serpentine on September 24, 2016 in London, England. The first ever Swim Serpentine, an open water swimming festival, is held on Saturday which sees around 4000 competitors swim a one mile course in the Serpentine lake in Hyde Park. (Photo by Jack Taylor/Getty Images)
