Bioluminescence refers to the ability of certain organisms to produce their own light through chemical reactions. It is common in many marine species, including fish, jellyfish, crustaceans, and cephalopods. This ability is especially prevalent in the deep sea, where natural sunlight cannot penetrate. Bioluminescence occurs in about 76% of deep-sea animals in certain regions, such as the eastern Pacific. These creatures emit light mainly in the blue and green parts of the spectrum, though some species can emit red or yellow light. This phenomenon is particularly fascinating because it challenges the traditional idea that there is no light in the deep ocean, which is typically seen as a "dark" environment. In fact, bioluminescent animals create their own light, allowing them to see and communicate in the darkness of the ocean's depths. This was a scientific discovery of modern times, but the Quran alluded to it centuries ago.

In Quran 24:40, Allah describes a scenario where a person is in the depths of the ocean, surrounded by waves and clouds of darkness. The verse reads:

This verse paints a picture of utter darkness where, despite being in the depths of the ocean, Allah can still provide light to the individual. This light is not from the sun, as the sunlight cannot reach that far below the surface, but it could refer to bioluminescence—light produced by organisms living in those depths.