Along the San Diego coastline, after night falls, look closely and you might see a neon, purplish-blue light out in the ocean, an effect of the phenomenon of the “red tide.”


Bioluminescent phytoplankton create their own light during a red tide in the rolling surf along the coast of Leucadia, Calif. (MIKE BLAKE/REUTERS)

During the day, the ocean is colored a rusty red, but at night, the bioluminescent phytoplankton give a spectacular light show.

A writer at the Orange-County Register offers a tip on how to get the most out of the red tide at Doheny State Beach:

In areas where the red tide was thick during the day, go to the damp sand at night and kick it up. The sand will light up like lightning, bursts that last just moments but will trip you out and have you kicking sand up for hours.

Surfers who swim in the red tide at night have reported that their movement in the water left a glowing trail behind.

The blue glow occurs when the organisms in the water are “jostled,” causing a chemical reaction that gives off a flash of light, explained Peter J. Franks of the Scripps Institution of Oceanography on the blog Deep-Sea News .

Kevin Baird, who has been posting photos of the surf, referred to the glow as “SpongeBob’s aurora borealis.”

Experts say the red tide could stay around for several more weeks or months.