The red tide is an annual phenomenon – an algal bloom colors the water brown (hence “red” tide), usually in summer or early autumn, but it may also occur earlier in the year. Unlike the red tide in Florida and other areas, the one at the San Diego coast isn’t toxic, or only very mildly toxic, and not a threat to public health. It’s just rather ugly during the daytime. ;-)

It’s a different story at night – the algae are bioluminescent, and the breaking waves at the shoreline excite them enough for a chemical reaction to occur that makes them emit their faint blue glow. Even kicking the wet sand with one’s feet will cause the reaction. This year, the red tide was exceptionally strong – rumor has it that a raw sewage spill (ewwww!) during a summer power outage furthered the growth of the algae…

It’s really beautiful, though – and pretty hard to capture with a camera, obviously. The glow is not very strong and only visible when it’s dark… and photography is about capturing light. :) So that means really long exposure times with blurring of water and wave movement – including the blue glow.