A light ray is composed of seven colours. These seven colours are Violet, Indigo, Blue, Green, Yellow, Orange and Red (VIBGYOR). The light ray undergoes refraction when it hits water. The upper 10 to 15 metres of
water absorb the red colour. Therefore if a diver is 25 metres under water and gets wounded, he would not be able to see the red colour of his blood, because the red colour does not reach this depth. Similarly orange rays are absorbed at 30 to 50 metres, yellow at 50 to 100 metres, green at 100 to 200 metres, and finally, blue beyond 200 metres and violet and indigo above 200 metres. Due to successive disappearance of colour, one layer after another, the ocean progressively becomes darker, i.e. darkness takes place in layers of light. Below a depth of 1000 meters there is complete darkness. 10