Following the death of his grandfather Haakon VII in 1957, Harald became crown prince as his father became king. A keen sportsman, he represented Norway in sailing at the 1964, 1968, and 1972 Olympic Games, and later became patron of World Sailing. Harald married Sonja Haraldsen in 1968, their relationship having initially being controversial due to her status as a commoner. The couple had two children, Märtha Louise and Haakon. Harald succeeded his father as king in 1991, with Haakon becoming his heir apparent.