Two effects caused by refraction of light are:

1) A swimming pool always looks shallower than it really is, because the light coming from the bottom of the pool bends when it comes out at the surface due to refraction of light.

2) A straight stick which is immersed partly in water always looks to be bent at the surface of water, because the light coming from the stick bends when it comes out at the surface due to refraction of light.