Darkness in a deep sea

The ayah in tafsir

Bahr lujji is a deep, fathomless sea. Wave above wave, then cloud. Darknesses stacked. The parable is of the kafir’s deeds: no light if Allah gives no light. The picture, though, is of a real sea the Arabs of the Hijaz did not dive.

What later eyes saw

In the open ocean, sunlight is gone within a few hundred metres. Below that, perpetual dark. Internal waves ride on density layers under surface waves. Clouds take still more light. Layered darkness is the literal structure of the deep. The parable borrowed a sea almost no listener had seen from the inside.

Where we stop

The ayah’s purpose is the heart, not an oceanographic chart. That the similitude is physically exact is a sign. It is not the tafsir of the verse’s warning.