What is "FAITH"

[Bad Writer]

Direct contradiction. The key to a healthy conversation.
But I can understand where your coming from, as the water actually DOES appear to be blue, as all colors truly do. Like Walking Void said, color itself is illusion.

He said that? Where?

You seem to have a poor understanding of what an illusion means and how it relates to the concept of color.

The color of an object is determined by the wavelength of light given out by it and received by our eyes. Whether that object itself is a source of light or the light is reflected or refracted or diffused in any other way is immaterial. An object gives out a particular wavelength of light - whether as a source or reflected - and that determines its color. That is not an illusion. That is objective reality.

That the color of an object changes with the change in nature and intensity of light on it or around it does not make it a illusion. It simply means that the color actually does change. When we say that an apple is red, we do not mean that it gives out the light with wavelength corresponding to the color red regardless of everything else. We mean that under white, the light reflected from it most closely approximates to the wavelength of color red. The term "under white light" is an unspoken premise. Saying that under blue light an apple is black is also factually correct. The black color is not an illusion.

An illusion would be the result of faulty perception. For example, in case of someone colorblind, the wavelength of light coming to his eyes would correspond to red, but due to lacking the necessary equipment he cannot correctly perceive it. Which is why, him perceiving the apple as grey would be an illusion. Its not necessarily a the result of of faulty perception either. For example, consider this image-



Here, the wavelength of the light coming from tiles A and B is the same - which is why they are of the same color. But because your mind is trained in perceiving objects in a particular manner, they appear to have different colors. Therefore this is an illusion - because the appearance does not match reality.

This is not a difficult concept to understand - or verify. All you need to do is eliminate the errors of human perception and compare the result. Get a machine that can identify colors without involving human perception in the process. If the conclusions of the machine match your own then what you are seeing is reality. If they don't, they what you are seeing is an illusion. You'll find out that in case of the given optical illusion, the machine correctly identifies tiles A and B as having the same color and in case of a pool, it identifies the color as blue. Therefore, the blue color of the pool is not an illusion.