Here’s one more reason to take a moonlit walk on the beach in San Diego.

Over the last few days, an algae bloom off the southern California coast between La Jolla and Encinitas has brought a red tide, creating a reddish haze during the day, and a spectacular light show at night.

The algae is filled with bioluminescent phytoplankton, which create an eerie, blue glow whenever it’s jostled around by the rolling waves. The glow can be seen in full view at night, about two hours after sunset, shining like a liquid version of the Northern Lights.

Bioluminescent tide (red tide) and short star trails at La Jolla Cove glows under a crescent moon.
Credit: Kevin Key/Getty Images

“The last time we had one was in September 2013, and the last big one was in October 2011,” Michael Latz, a bioluminescence expert at UC San Diego’s Scripps Institution of Oceanography, to told the San Diego Union-Tribune. “We can’t predict when these things occur, we don’t know how long they will last, when they’ll be here, and we really don’t understand the dynamics.”

According to SF Gate, the phenomenon usually happens once about every five years and lasts only a few days. Occasionally, they can happen more frequently.

According to the Scripps Institution, the phenomenon in San Diego is not known to be toxic, though very little is known about it.

Earlier this year, waves in Big Sur also lit up the night. Other places around the world where bioluminescence has been seen include Tasmania and Cape Town.