🌑 Aphotic Zone Light — Beer-Lambert Absorption

🌑 What It Demonstrates

Sunlight entering the ocean is absorbed according to the Beer-Lambert law: intensity decays exponentially with depth, I(z) = I₀ · e^−α·z. Crucially, the absorption coefficient α depends on wavelength. Red light (700 nm) is absorbed within the first 10–15 m, orange by ~40 m, yellow by ~100 m. Blue light (475 nm) penetrates the deepest, which is why the deep ocean appears blue-black. Below ~200 m — the aphotic zone — less than 1% of surface light remains, and photosynthesis becomes impossible.

How to Use

• Move your mouse over the canvas to see the light intensity at any depth.
• Adjust Max Depth to zoom in on the shallow photic zone or see the full deep column.
• Water Turbidity multiplies all absorption coefficients — turbid coastal water absorbs much faster than clear ocean water.
• Toggle Red fish silhouette to see why red-coloured deep-sea fish appear invisible at depth — there's no red light to reflect.

Did You Know?

Many deep-sea creatures are red because red light doesn't reach them — they appear jet-black to predators. Some deep-sea dragonfish have evolved bioluminescent organs that emit red light, giving them a "secret" searchlight invisible to other species. The deepest record of photosynthesis is ~270 m in extremely clear tropical water — achieved by specialised algae that can harvest the last blue photons.