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The surf is sparkling with neon light. Here’s where to see bioluminescence at local beaches

Bioluminescence can be seen at several spots along the San Diego County coast at night.
(Hayne Palmour IV)

The phenomenon, which is sporadic and hard to predict, is caused by phytoplankton when they tumble in the surf.

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Beach-goers are again fanning out in La Jolla and elsewhere along the San Diego County coast at night to watch the surf sparkle and flicker with enchanting blue neon light.

The phenomenon, which is sporadic and difficult to predict, is caused by bioluminescent plankton that light up when they tumble around in the surf or hit the legs of people walking in the ocean.

Initially, the bioluminesence was confined mostly to a handful of spots, including La Jolla Shores and Encinitas. But in the past few days, the bright flashes also have been reported at Black’s Beach, Point Loma, Sunset Cliffs, Oceanside, Tamarack Beach and Carlsbad Beach.

According to the Scripps Institution of Oceanography at UC San Diego in La Jolla, bioluminescence is caused by a red tide, a bloom of microscopic phytoplankton with a reddish-brown color. On sunny days, the organisms swim toward the surface, where they concentrate, resulting in an intensified coloration of the water. At night, when the phytoplankton are agitated by waves or other movement in the water, they emit a blue glow. Bioluminesence can become more visible when there’s strong surf.

‘The Michael Phelps of plankton’ can swim vertically and quickly between sunlight at the ocean surface and nutrients at the bottom to fuel their growth and enable them to congregate in large numbers.

Sept. 1, 2023

Lifeguards urge the public not to venture onto low-lying rocks at night to view the light flashes because it can be hard to see potentially dangerous incoming waves.

— La Jolla Light staff contributed to this report.