Snell's law states that:
n1 Sin∅1 = n2 Sin ∅2
Where, medium 1 with (n1 = 1.33) is water and medium 2 with (n2 = 1) is the air, ∅1 = 90-50 = 40°
Therefore,
Sin ∅2 = n1/n2 *Sin ∅1 = 1.33/1 *Sin 40 = 0.4833=> ∅1 = Sin ^- (0.4833) = 28.9 °
The fisherman the sun at 61.1° (90-∅2) above the horizontal.