Her distance from the turtle is the hypotenuse of a triangle with one leg equal to her height above the ocean floor...
sinα=h/d where h=her height, and d is her distance from the turtle...
d=h/sinα we are given that h=15ft and α=41° so
d=6/sin41 ft
d≈9.15 ft (to nearest one-hundredth of a foot)