Surah 24. An-Nur, Ayah 40

I.e., their bad deeds, as contrasted with their good deeds, which in the preceding verse have been likened to a mirage.

Lit., "one above another".

 This is another scientific fact mentioned in the Quran: the existence of underwater waves, like layers.

A contrast to "Light upon Light" in xxiv. 35 above.

The true source of Light in the world of Reatity is Allah, and anyone who cuts himself off from that Light is in utter darkness indeed, for it is the negation of the only true light, and not merely relative darkness, like that which we see, say, in the shadows of moonlight.

What a graphic picture of darkness in the depths of the Ocean, wave upon wave, and on top of all, dense dark clouds! There is so little light even in ordinary depths of the Ocean that fishes which live there lose their eyes as useless organs.