This pretty blonde high school junior from Ridgewood, N.J. has her bright blue eyes focused firmly on the Olympic Games. Carin, who learned to swim at the age of 6 as a "safety precaution," won her first national title in 1953 and, at 16, is the first to hold all four American women's backstroke crowns (100 and 200 yards, 100 and 200 meters). Two weeks ago, in the AAU meets at Tyler, Texas, she swooshed to new U.S. records of 1:14.5 for the 100 meters and 2:43.8 for the 200 meters. Her next goal: the Olympic tryouts in Detroit, August 7-10 and a trip to Melbourne.