Slobodan, the upper McKenzie is famous for its blue pools. The water itself is very pure and clear, but in deeper places, like the head and middle of this pool, wavelengths longer than blue are filtered out by the water itself. It also picks up some of the color from the sky, especially where there is a bit of churning from a small rapid, as here. I could see this blue area from the top of a nearby hill, which is what attracted me to it. It is real, but smoothed out a bit from the slow shutter speed.
