Most of the seas and oceans are covered with thick culumus clouds that block a great proportion of sunlight, as is sown by most satellite pictures. these clouds reflect back a lot of the sun's rays and keep out a lot of its light. Of the light that remainis, the ater reflect back a great deal of it, and absorbs the rest, so that the light decreases the deeper you go in the water. In his book Marines Optict, Gerloff says that the level of light in the water of the ocean is reducedat a depth of 35 metters to ten percent of its level at the surface, and to 1 percent at a depth of 85 metetes, and to 0,1 percent at a depth of 135 metters, and to 0,01 percent at a depth 190 metters. After a depth of 1,000 metters the darkness grows so deep that there is virtually no visibiliti and if a man stretches out his hand, he would not be able to se it.
These astonishing scientific facts are mentioned in the Holy Qur'an which came down to Arabs in the desrts who did not know how to swim or sail in the sea an oceans. In the fortieth Verse of Al-Noor, Allah Most High, says:
أَوْ كَظُلُمَٰتٍۢ فِى بَحْرٍۢ لُّجِّىٍّۢ يَغْشَىٰهُ مَوْجٌۭ مِّن فَوْقِهِۦ مَوْجٌۭ مِّن فَوْقِهِۦ سَحَابٌۭ ۚ ظُلُمَٰتٌۢ بَعْضُهَا فَوْقَ بَعْضٍ
إِذَآ أَخْرَجَ يَدَهُۥ لَمْ يَكَدْ يَرَىٰهَا ۗ وَمَن لَّمْ يَجْعَلِ ٱللَّهُ لَهُۥ نُورًۭا فَمَا لَهُۥ مِن نُّورٍ
"Or the (state of a disbeliever) is like the darkness in a vast deep sea, overwhelmed with waves topped by waves, topped by dark clouds, (layer of) darkness upon darkness: if a man stretches out his hand, he can hardly see it! And he for whom Allah has not appointed light, for him there ia no light."
Hence, Allah, the Exalted, says ''Zulumaat" (usually translated as"darkness" although it is a plural form, e.i., darkness), and He did not say "Zulmah" (singular). He said: " (layer of) darkness upon darkness" (lit. darknesses one above another).



