Deformation in the water surface focussing light.
Talking about how a deformation in the surface leads to light being focussed in different ways here and here, another example came to my mind. Remember how my mom and I were watching the standing waves at the Pinnau a while back? That was the same place where we also observed the “shadows” of the eddies, so as we were playing with water and light anyway, this happened:
See how the stick is deforming the water surface? This again leads to a focussing of light at the ground which you can observe if you follow the stick until you reach the ground and then follow its shadow.