For one of Hong Kong's youngest Paralympians, swimmer Kelvin Tang Wai-lok, success came quickly when the 15-year-old emerged as a serious contender to compete in the London games a year ago. Tang, who has a mild mental impairment, will be among 28 athletes competing in seven sports at the London Paralympic Games, which begin on Wednesday and run until September 9. The teenager will represent Hong Kong in three swimming events: the 100-metre breaststroke, 100m backstroke and 200m freestyle. Tang's mother, Vicky Ng Chun-hung, was delighted with her son's achievement: "He exudes so much joy when he sees his time improve - it's something money can't buy." The sport has also helped Tang make friends. "I'll eat breakfast with my teammates after training," he told the Sunday Morning Post during a recent visit to a training session. "When I'm nervous before a race, it helps to chat with them." Intellectually impaired athletes compete separately from the physically disabled in the Paralympic Games. But no competition was held for the intellectually impaired in the 2004 Athens Games after the winning Spanish basketball team in the 2000 Sydney Games was found to have no learning impediments. This year, a system for classifying mentally impaired athletes was established for the Paralympics - which stands for the parallel Olympics. Tang, who studies at Choi Jun School in Tai Wai for the learning impaired, will be one of five local swimmers in London. He competed in an international race for the first time last April, in the UK. He quickly become the fastest swimmer on his team, and his consistent performances convinced the coach to reshuffle the Paralympic line-up. His coach of three years, Ni Chaoyang, said Tang's strongest event was the 200m freestyle. "He has strong muscles and is an explosive swimmer," she said. A torpedo in water, Tang's softer side emerged by the poolside, giggling sweetly as bystanders praised his taut muscles. Ni, a firm instructor, exuded maternal warmth as they exchanged jokes. Tang shares the title of Hong Kong's youngest Paralympian at London with 15-year-old Natasha Tse Pui-ting, who will compete in equestrian dressage for the physically disabled. Another first-time Paralympian is 18-year-old Yeung Hiu-lam, who will compete in boccia, a sport where wheelchair-bound athletes throw balls as close as possible to a target ball. Yeung, who has cerebral palsy, began playing the sport in 2009. "We'll be bringing hand warmers with us to London; they help with our throws," he said.