Video: What is the blue glow in the ocean off the California coast?

(KTLA) — For the past month, Southern California’s coastal tour operators have been busy tracking a rare pod of killer whales. Now, they’re offering an entirely different experience once the sun goes down.

Bioluminescent microalgae create a natural blue glow when the water is stirred up.

Finding high concentrations of the algae can be hit or miss, but the sightings have been common enough lately that whale-watching services are now offering cruises for anyone hoping to experience the sight for themselves.

“Jump on board with us on the search for the Bioluminescence glow that illuminates the night sky as the waves crash around the shorelines, wake from our ships, possible dolphin swimming through, large fish schools, and anything else that triggers the blue natural phenomenon,” the whale watching company advertises,” writes Newport Coastal Adventures of their nightly 90-minute cruises.

The company has also released video and photos of the glowing water, including several stunning views of a circling boat from above.

The bioluminescence also put on a spectacular show for SoCal beachgoers in September 2023, when boogie boarders were videotaped ripping through glowing waves in Huntington Beach.

Nate Jaros, senior director of fish and invertebrates at the Aquarium of the Pacific, told NewsNation affiliate KTLA that the microalgae, called a dinoflagellate, is associated with a red tide that is visible during the day and creates a glow when churned up at night. 

“It’s the same type of organism when you have a red tide, which gives the water kind of an orangish brown, red kind of tint when they are in high density during the day,” he said. “But at night when disturbed, they produce bioluminescence. So, when there’s a lot of agitation in the surf, it can activate that bioluminescence which makes the waves appear to be glowing.”