The Red Tide – Bioluminescence in San Diego


It's that time of the year that all San Diegans and tourists from far and near are looking forward to. And that is the bioluminescent waves that happen yearly on the shores of the Southern California beaches from as far north as Santa Barbara, Malibu, Venice Beach all the way down to San Diego and Mexico.

These magical electric blue waves are caused by the red tide. The red tide happens when microorganisms called dinoflagellates are in bloom. Dinoflagellates use bioluminescence as a form of predator avoidance. That means that when a small fish tries to eat the algae, the algae produce this beautiful blue light that attracts bigger predators which instead eat the small fish. Pretty clever for a single-cell organism, right?

So, if it produces a blue light why is it called the RED tide? During the day these tiny creatures come to the surface of the water where they concentrate for sunlight. This results in an intense reddish coloration of the waves, thus the name Red Tide. During the night, however, if agitated by the waves or any other movement in the water, the algae emit the dazzling blue light.

When Can The Red Tide Be Observed in San Diego?

The beautiful display of light can be observed on San Diegan beaches anytime from April to October and last for days like in May 2018, one to two weeks like September 2013 and June 2019 or even close to one month like the red tide in April 2020.

Red tides are unpredictable and not all of them produce bioluminescence, according to Scripps Institution of Oceanography. Scientists do not know how long the displays will last or exactly when they will occur."We know it's happening because we see it", they say. So, keep an eye open to the waves turning red. That's when you are most likely to observe bioluminescent ocean waves in San Diego.?

Where Do Red Tides Occur In The USA?

There are several places in the world where bioluminescence occurs and few of them are located in the USA. This phenomenon can be observed on both East and West Coasts of the United States.

  • Mission Bay, San Diego, CA
  • Torrey Pines, San Diego, CA
  • Manasquan Beach, Nj
  • Cortez, FL

Bioluminescence can also be observed around the world in places like:

  • Cairns, Australia
  • Gippsland Lakes, Australia
  • Luminous Lagoon, Trelawny, Jamaica
  • Mosquito Bay, Vieques, Puerto Rico
  • Halong Bay, Vietnam
  • Bali, Indonesia

How To Take A Great Picture Of The Bioluminescent Red Tide?

Dinoflagellates, the small algae that make up the red tide can only glow for a split-second or so every 24 hours. There are millions of them in the water making the glow appear continuous, which means the best way to capture a great picture of the bioluminescence is by using a tripod and taking a long exposure shot capturing the millions of tiny millisecond-long glows that make up the illumination.

Another factor to take into consideration when planning your trip to San Diego to see the bioluminescence is the phase of the moon. Moonlight is also key for great night-time pictures of the red tide so going out on a crescent or full moon will ensure you take the best photos of bioluminescent San Diegan waves. Add the two together, a full moon and the glowing blue ocean and you have yourself a fairytale background where all beautiful things are possible.

What Should I Bring To The Beach For The Bioluminescence Display?

The best time at night to observe the bioluminescent display in San Diego is when it gets completely dark, 1 or 2 hours after sunset, so around 10 - 11 PM. Remember even sunny San Diego can get a little chilly at night so if you want to be able to spend a couple of hours enjoying the light show, bring with warm clothing and wear some comfortable shoes. You can bring any food or drinks you would like to enjoy a relaxing night on the beach.

Don't forget your camera and a beach towel or picnic blanket to sit on the beach. Also, very important: bug spray or sunscreen is not allowed because of the harmful effect they have on the microorganisms. You can use non -DEET bug spray, which we highly recommend if you want to peacefully enjoy the night and not scratch your skin off for the following days, but refrain from wearing strong perfumes or hairsprays.

Is The Red Tide In San Diego Toxic?

Scientists say these tiny creatures can emit toxins that might irritate those with underlying breathing problems like asthma or other chronic respiratory issues. These people, doctors say, should avoid red tides. Symptoms from breathing red tide toxins can include coughing, sneezing, and teary eyes. For most people, it is safe to swim in the red tidewaters, but this can cause skin irritation and burning eyes. Do not swim among dead fish because they can be associated with harmful bacteria.

The Perfect Accommodation To Return To After Seeing The Bioluminescent Ocean

After a couple of perfect hours spent on the beach listening to the ocean roar, it is now time to finish the night in luxury. You have enjoyed the dazzling neon blue lights showcased by talented little performers and you can now retire to one of our welcoming vacation rentals in Cardiff by-the-Sea. Our homes provide the perfect place for a good night's sleep or some peaceful time on the deck to contemplate the spectacle witnessed. ?Book either one of our comfortable, welcoming vacation homes and take in the beautiful nigh-scenery Cardiff by-the-Sea has to offer. Choose between our Penthouse, Parkhouse, or Seacottage, pour yourselves a glass of Californian wine, and relax.