Clifford Douglas "Cliff" Lumsdon Jr. (April 13, 1931 – August 31, 1991) was a remarkable Canadian world champion marathon swimmer.
Cliff Lumsdon turned professional when he was 16 and would later say that the only regret in his career was giving up his amateur status before the 1948 Summer Olympics. At the age of eighteen Lumsdon won the world marathon championship in Toronto defeating 46 competitors in the annual 15-mile race at the Canadian National Exhibition with a 7 hour, 54 minute and 55 second swim. He not only won the race but led all laps. Lumsdon was accompanied for part of the race by his fiancée and by fellow Lakeshore swimmer Marilyn Bell, riding in a boat. On the strength of that victory he was awarded the Lou Marsh Trophy as Canada's top athlete of 1949. Lumsdon won five world championships earning him the unofficial title of “the King” of professional swimmers.
Lumsdon won the 26-mile Atlantic City marathon in 1956. That same year he became the first swimmer ever to cross the treacherous Straits of Juan de Fuqua between Vancouver Island and Washington State. He retired in 1965.
He coached his daughter, Kim Lumsdon, who was also a top marathon swimmer and accompanied her during her swim across Lake Ontario in 1976. He was made a Member of the Order of Canada in 1982. In 1988 a waterfront park in Toronto was named Cliff Lumsdon Park in his honour. Lumsdon died in 1991 at age 60.
Mr. Lumsdon is a member of Canada’s Sports Hall of Fame.