The video: Wide-eyed surfers in Southern California are paddling out long after sunset these days. That's because a phenomenon known as red tide that turns the ocean a reddish clay color during the day — thanks to large masses of algae — is causing something peculiar at night, too: Glow-in-the-dark waves that flash "spectacular neon blue," says Tony Barboza of the Los Angeles Times. (Watch a video below.) The "dazzling" effect is due to creatures lurking in the algae bloom: Bioluminescent phytoplankton, which have been floating along San Diego coasts since late August. When huge numbers of these tiny creatures are disturbed simultaneously — either by a crashing wave or a surfer's speeding fins — a chemical reaction takes place, emitting a flash of light that's visible at night.
The reaction: The waves look like "a night light sent from King Triton himself," says Jillian Anthony at GOOD. The whole scene is indeed a "beautiful hallucination," says Brent Rose at Gizmodo. But beware: The CDC warns that red tides can sometimes cause eye and nose irritation, coughing, and shortness of breath. So if you must ride, make sure to have "a neti pot handy." Watch surfers carve up these glowing blue waves: