User blog comment:Kacj321/Eurogamer 2011/@comment-72.89.169.3-20110925230742

"You know how in Fallout you can rest the camer directly on water level and see everything clear as day underwater, but if you go under there's a green tint? Exactly like that in this; although the shift is actually more noticeable"

That sounds very similar to how water is in REAL LIFE.