This is slightly off topic, but...
I was one of those children that local instructors had not managed to get in the water. I learned to swim when my mother, father and I spend a weeks vacation on a North Sea island. Later, when I was 6, I joined the local swim club and swam competitive for 15 years. Have been swimming and scuba diving for fun since.
So I guess showing the kid that it's possible to have fun in water would be my priority.