Lighting is not uniform underwater

[Peregrine05]

The lighting underneath the surface of the water is not uniform. When viewed from above the surface of the water, The lighting becomes darker for the first block under the water surface, and periodic waves of brighter lighting are seen intersecting with the surface of the water at the top corners of the blocks. The next blocks underneath cut into brighter lighting and then continue with a more normal lighting.

When viewed from underneath the surface of the water, the lighting cutoffs are not visible, and a similar effect of periodic waves of brighter lighting is seen aligning with the edges of the blocks.