An underwater diver sees the sun 50° above horizontal. how high is the sun above the horizon to a fisherman in a boat above the diver?

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.