Five-time Olympic champion swimmer Ian Thorpe has confirmed he will come out of retirement in a bid to compete at the 2012 Olympics in London. The 28-year-old Australian retired in 2006 and had denied several reports of a return to international swimming. Thorpe said his decision came after visiting the swimming venue in London, describing it as extraordinary. Thorpe had won three gold medals at the 2000 Games in Sydney and added two titles in Athens four years later.