Karen Margrethe Harup is one of only two Danish athletes to win three Olympic medals at the same Games (the other being Anders Peter Nielsen). For Harup, the 1948 Olympics were the culmination of her career. Hampered by the Second World War, she could first display her talent internationally only in 1947. At the European Championships in Monaco, she won three gold medals, in the 400 m freestyle, the 100 m backstroke and the 4 x 100 m relay. She would medal in the exact same events in London, winning the backstroke and placing second in the other two distances. When Harup retired the following year, she had amassed 30 Danish titles and had set two world records (both in relay events). This earned her a spot in the International Swimming Hall of Fame, in which she was inducted in 1975. Harup remained a swimmer her entire life, coaching swimmers of all ages well into her seventies.