An eerie phenomenon: Why waves in California are glowing blue

Breathtaking neon blue waves have been lighting up the ocean near San Diego, Calif., since Monday.

The rare phenomenon, known as bioluminescence, stretches about 28 kilometres along the coast and scientists are not sure how long it will last.

The illuminating colour is due to a microorganism in the water called dinoflagellates. It’s a type of algae that glows as a natural defence mechanism from predators that try to eat the blooms, according to Scripps Oceanography research scientist, Dimitri Deheyn.

“The algae makes a light when a fish or little shrimp tries to eat it,” Deheyn told NBC News. “That light attracts a bigger fish that can eat whatever is trying to eat the algae.”

The bioluminescence is common in nature among other species too, such as fireflies and glow worms.

The phenomenon along the coast is also known as a red tide because during the day the microorganisms give the water a reddish hue, but at night they glow where they are disturbed by waves.

The last time the shores of San Diego were lit up by a bioluminescence-producing red tide was in 2013. It lasted for about a week.

If you live in the area, Scripps Oceanography said the best time to catch the glowing activity is from a dark beach at least two hours after sunset.

WATCH: Glowing blue algae lights up the shore of a Tasmanian bay

0:58 Glowing blue algae lights up the shore of a Tasmanian bay