Refraction and spearing a fish
We now know that a light ray travelling from air to water will be refracted (change direction) but so too does light from water to air.
This means that if you are trying to spear a fish in the water
you must make adjustment.
Adjust the angle of throw.
This effect becomes even more acute when the angle of light ray is even more shallow.
Notice too that the fish appears to be at a shallow depth but it is a lot deeper in actuality.
The refraction of light at the surface of water makes ponds and swimming pools appear to be a lot shallower than they really are.