Payne was born to British parents in 1987 in Johannesburg, South Africa and started swimming aged four. She took to it like, well, a duck takes to water - she could do front crawl at age five and had mastered all the strokes by age seven. As she later recalled, "at eight I was pulled up an age group because I was beating all the eight-year-olds - until the parents of the nine-year-olds made me go back down because I was beating them too!"
At that time, she was spotted by British Swimming's national performance director Bill Sweetenham at a South African training camp and it led to the family deciding to return to the UK so that Keri-Anne could train at British Swimming's Intensive Training Centre in Stockport, Greater Manchester.
At 15, Keri-Anne broke the British junior 800-metre freestyle record but, unfortunately, she failed to win a medal at the 2006 Commonwealth Games four years later and her funding was cut. It was then that her coach, Sean Kelly, suggested that she try open-water swimming, which would allow her to access additional financial support. It was to prove a turning point. At the 2008 Summer Olympics in Beijing, Keri-Anne placed second in the 10-kilometre open-water event and won a silver medal.
The following year, at the World Aquatics Championships in Rome, she won the 10-kilometre open- water race and then, two years later, reclaimed the World Championship gold in Shanghai becoming, in the process, the first British athlete in any sport to confirm qualification for the 2012 Summer Olympic Games.
So, it's fair to say, things have gone swimmingly for Keri-Anne and, thanks to an early encounter with jellyfish, she's more than comfortable with the open-water environment. "I'm lucky," she once said, "the second open-water swim I did, thousands of jellyfish were stinging me everywhere so there isn't really anything that fazes me now. Except sharks."