Shallow tropical water. Eight Gerstner waves displace the surface in the vertex shader and give it an exact normal — the surface is a closed-form function of position, so the normal comes from two real tangents rather than from differencing a height map. The fragment refracts the view down to a lit seabed and attenuates what returns per colour channel: red is absorbed roughly ten times faster than blue-green, and that ratio alone is where the turquoise comes from. Foam keys off steepness rather than height, so it breaks on tilted faces instead of capping every crest. A slow noise scales the whole wave sum, giving patches of calmer and rougher water — without it eight waves still read as one uniform field. Every shader was compiled at build time, so the page starts immediately.