Home▸Physics & Mechanics▸Water Caustics Refraction Simulator

💧 Water Caustics: How Snell's Law Paints Light on a Pool Floor

Interactive 3D pool-water surface where adjusting wave amplitude and light angle shows refracted rays converging into shifting caustic light patterns on the pool floor below, per Snell's law.

Physics & Mechanics3DModerate60 FPS

An interactive 3D pool where a rippling water surface bends sunlight according to Snell's law, tracing each refracted ray down to the floor to build the shifting bright-and-dark caustic net swimmers see underwater.

🔬 What It Demonstrates

Local surface tilt determines how much each point on the water bends incoming light. Rays refracted toward a common spot pile up into bright caustic lines; rays bent apart leave dim gaps — all governed by n₁sinθ₁ = n₂sinθ₂.

🎮 How to Use

Raise wave amplitude to sharpen the caustic net, tilt the sun angle to shift the pattern, and change pool depth to see the caustic focus tighten or blur. Toggle ray lines to see individual refracted paths.

💡 Did You Know?

The same caustic optics that light up a pool floor also form rainbows, the bright ring inside a coffee cup, and the crescent-shaped sunlight patches under trees during a partial solar eclipse.

⚙ Under the hood

Interactive 3D pool where rippling the water surface shows how Snell's law refracts sunlight into the shifting caustic light patterns painted on the pool floor.

water-causticssnells-lawrefractionopticslight-focusingwave-simulationphysics

3D · Three.js / WebGL renderer · 60 FPS target · runs fully client-side, no install