Prof. Durga Rao is an expert in the field of Marine Geology and was a professor at King Abdul Aziz University in Jeddah. He was asked to comment on the following verse: "Or (the Unbelievers' state) Is like the depths of darkness In a vast deep ocean, Overwhelmed with billow Topped by billow, Topped by (dark) clouds: Depths of darkness, one Above another: if a man Stretches out his hand, He can hardly see it! For any to whom Allah Giveth not light, there is no light!" [Al-Qur'an 24:40]
Prof. Rao said that scientists have only now been able to confirm, with the help of modern equipment that there is darkness in the depths of the ocean. Humans are unable to dive unaided underwater for more than 20 to 30 meters, and cannot survive in the deep oceanic regions at a depth of more than 200 meters. This verse does not refer to all seas because not every sea can be described as having accumulated darkness layered one over another. It refers especially to a deep sea or deep ocean, as the Qur'an says, "darkness in a vast deep ocean". This layered darkness in a deep ocean is the result of two causes:
1- A light ray is composed of seven colors. These seven colors are Violet, Indigo, Blue, Green, Yellow, Orange and Red (VIBGYOR). The light ray undergoes refraction when it hits water. The upper 10 to 15 meters of water absorb the red color. Therefore if a diver is 25 meters under water and gets wounded, he would not be able to see the red color of his blood, because the red color does not reach this depth. Similarly orange rays are absorbed at 30 to 50 meters, yellow at 50 to 100 meters, green at 100 to 200 meters, and finally, blue beyond 200 meters and violet and indigo above 200 meters. Due to successive disappearance of color, 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 [Oceans, Elder and Pernetta, p. 27].
2- The sun's rays are absorbed by clouds, which in turn scatter light rays thus causing a layer of darkness under the clouds. This is the first layer of darkness. When light rays reach the surface of the ocean they are reflected by the wave surface giving it a shiny appearance. Therefore it is the waves which reflect light and cause darkness. The unreflected light penetrates into the depths of the ocean. Therefore the ocean has two parts. The surface characterized by light and warmth and the depth characterized by darkness. The surface is further separated from the deep part of the ocean by waves.
The internal waves cover the deep waters of seas and oceans because the deep waters have a higher density than the waters above them. The darkness begins below the internal waves. Even the fish in the depths of the ocean cannot see; their only source of light is from their own bodies.
The Qur'an rightly mentions: "Darkness in a vast deep ocean overwhelmed with waves topped by waves". In other words, above these waves there are more types of waves, i.e. those found on the surface of the ocean. The Qur'anic verse continues, "topped by (dark) clouds; depths of darkness, one above another." These clouds as explained are barriers one over the other that further cause darkness by absorption of colors at different levels.
Prof. Durga Rao concluded by saying, "1400 years ago a normal human being could not explain this phenomenon in so much detail. Thus the information must have come from a supernatural source".
(from "The Quran and Modern Science, Compatible or Incompatible?" by "Dr. Zakir Abdul Karim Naik" published by Darussalam)