Why is water transparent ?

Water is made up of very simple molecules oxygen and hydrogen that are unable to absorb too much energy.

Therefore, when visible light pass through the water, it is unable to absorb too much of visible light or energy.

The difference between the energies of the two quantum states of water is very less, therefore, complementary colour is not generated.

Water reflects very small amount of light. And reflects all the radiation in the visible spectrum equally.

(Equally means as their proportion exists in visible spectrum; i.e. sunlight) All seven colours equally means resultant is colourless.

Water is highly transparent and allows most of the light to pass through it. Again in the same proportion. So the passed through light also appears white.

While relatively small quantities of water appear to be colorless, water's tint becomes a deeper blue as the thickness of the observed sample increases.

The blue hue of water is an intrinsic property and is caused by selective absorption and scattering of white light.

Impurities dissolved or suspended in water may give water different colored appearances.

Any colour that we all see is actually that wavelength of light which was not absorbed by that particular substance and was reflected back to reach our eyes.

Water does not reflect back any colour except a small bit of blue colour.

Hence, small quantities of water appear to be colourless.

But water's tint becomes a deeper blue as the thickness of the observed sample of water increases.

The blue hue of water is an intrinsic property and is caused by selective absorption and scattering of white light.

water is transparent because eyes first evolved in water. The range of the EM spectrum we detect corresponds to the spectrum for which water is transparent (absorbs the least).

Water has a tri-atomic structure which does not absorb any colors from visible spectrum of the light.

All the absorption occurs in the ultraviolet region of the electromagnetic spectrum of light, which is not responsible for imparting any color to a substance.

However, According to Dr. Martin Chaplin the molecule’s two hydrogen atoms sit at the ends joined midway by the oxygen atom.

Had we evolved in mercury, we would think mercury is transparent and detect EM waves that pass through mercury.

The resulting V-shaped combination can vibrate in various ways, mopping up different wavelengths of light.

Water is transparent due to the fact that the molecules are not condensed, but far apart in the molecular level; Therefore, light passes through water easier than it does cement, or a wall.

But it’s particularly effective at absorbing longer, redder wavelengths, while leaving shorter, bluer wavelengths fairly untouched.

Once light from the sun hits an object, the object absorbs part of the light (lets say blue and yellow), but the other part (red) deflects and hits the pupil of our eyes. From there, our brains translate this type of light as the color that you see.

Water scatters shorter wavelengths more effectively, leading to more of the blue component of sunlight reaching our eyes.The result is a pale blue colour. So, the water appears pale blue in sea.

However, water is different. When light hits water, there is about a 10% chance (maybe 20%) that the light will actually hit the water, because the water is not dense, but spread apart.