1400 years ago, no one knew that visible light cannot penetrate deep ocean waters. This fact, however, was described in the Quran long before it was discovered by modern science.

The photic zone refers to the upper layer of the ocean that receives enough light for photosynthesis and for humans to see without artificial aid. Light from the sun only penetrates to a certain depth in the ocean, typically around 200 meters in clear water, beyond which it becomes pitch dark. This zone where visible light diminishes is known as the euphotic depth, and the intensity of light falls to just 1% of its surface value.

The Quran, in verse 24:40, describes the phenomenon of darkness in deep waters:

- The Arabic term "Lujji" (لُجّيّ) refers to the deep, dark ocean. - The verse describes multiple layers of darkness, "depths of darkness, one above another," which aligns with the concept of light attenuation in the ocean. Each "wave topped by waves" metaphorically corresponds to the layers of water, with darkness increasing as the depth increases.

The Quran describes darkness so profound in the deep ocean that a person cannot see their own hand, indicating that light does not penetrate to that depth. This is a scientific fact about the photic zone—light does not reach beyond certain depths, leaving the ocean dark. How could an unlettered man living 1400 years ago have known that visible light cannot reach deep waters, especially when this concept was only confirmed in modern times through scientific exploration of ocean depths? This remarkable alignment between the Quranic description and modern oceanography raises questions about the source of such knowledge, suggesting it was not known by people at the time.