What is Bioluminescent Water? 6 Best Places to Spot Glowing Water

Bioluminescence is the light produced by a living organism. Anything that lives can produce bioluminescence, even humans, but not all do.

A chemical reaction is required for an organism to produce bioluminescence.

When the organic compound Luciferin combines with oxygen, an enzymatic reaction occurs Luciferase catalyzes that. This reaction produces a substance called oxyluciferin. It is this luminescence product that produces light.

What is Bioluminescent Water?

Nearly all bioluminescent organisms, including the sharks we’ve discussed in previous articles, produce light this way.

Some light-producing organisms use photo-proteins instead of Luciferin. “Most photoproteins are found in marine organisms,” including some jellyfish, corals, fish, and bacteria. Fireflies also use this mechanism to produce light.

What is Bioluminescent Water?

Bioluminescent water occurs when millions of tiny bioluminescent organisms group together. Each one produces bioluminescence, turning the ocean blue with glittering neon blue lights.

What Causes Bioluminescence Waves?

Bioluminescence waves occur when bioluminescent organisms are stimulated externally, causing them to release light.

As the coastal waves toss the organisms, algae, and plankton around, so they respond with a glowing blue light.

During the day, an algae bloom appears red due to the natural “sunscreen” produced by these organisms. At night, bioluminescent light produces them into a shimmering sea of electric blue.

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Anything moving through the ocean will leave a glowing trail behind it as the bioluminescent dinoflagellates light up in response to their movement.

Why Does Bioluminescence Occur?

Scientists are still unsure of why certain organisms emit bioluminescent light. Some species appear to attract a mate, while others use it as camouflage.

For instance, the underside of the cookie-cutter shark glows a pale blue-green that replicates the light filtering through from the surface. As a result, the shark is almost invisible to predators underneath it.

Why Does Bioluminescence Occur?

Dinoflagellates also appear to use bioluminescence as a form of defense, lighting up when they detect a predator, possibily in an attempt to draw attention to the predator and away from themselves.

Deep-sea fish, on the other hand, use bioluminescent light to attract prey. Dragonfish and angler fish have appendages on their heads that look a little like fishing rods.

These contain bioluminescent bacteria that the fish use to lure their prey to within striking distance.

Can You Swim in Bioluminescent Water?

There are a couple of places where you can swim in bioluminescent water: Laguna Grande in Puerto Rico. But, most importantly, swimming in bioluminescent water isn’t recommended.

Human bodies carry all kinds of contaminants that could harm tiny light-producing organisms. Similarly, as small as they are, some dinoflagellates can threaten humans.

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The dinoflagellate Pyrodinium bahamense is one of the most dangerous and also one of the most abundant.

Can You Swim in Bioluminescent Water

It produces saxitoxins, or paralytic shellfish poisons, interrupting the transmission of nerve signals, causing paralysis and, in severe cases, death.

To be affected by saxitoxins, humans usually need to ingest them, but even swimming among them can have unpleasant side effects. These include irritation of the skin, burning eyes, and respiratory distress.

The presence of bioluminescent water is even more dangerous for other marine life, and for anyone eating them. Not only can the layer of plankton be so thick it deprives the creatures beneath it of oxygen, but it also releases toxins that accumulate in shellfish, making them toxic as well.

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While swimming in bioluminescent water won’t kill you, swimming in waters contaminated by dead fish could. As the fish decompose, they release bacteria from their bodies. The combination of toxins from the glowing plankton and bacteria from the decomposing fish make swimming in bioluminescent water potentially dangerous.

According to Dr. John Sinnott, the Chairman of Internal Medicine at USF Health, “Most people, not everybody, but most will get very irritated eyes.

They’ll begin coughing, have a runny nose, and if they have asthma or chronic lung disease, [it] will really act up.” 

Other people may experience a sore throat, skin irritation, and headaches.

Although these symptoms are usually short-lived and easily counteracted by washing with fresh water, swimming in bioluminescent water is best avoided.

Is Bioluminescence Hot?

Unlike most light sources on earth, bioluminescence is a cold light. While electricity, for example, produces almost as much heat as it does light, bioluminescence generates less than 20% thermal radiation.

As it is a cold light, it often appears blue, although some marine creatures produce red or yellow light.

Is Bioluminescence Hot?

The actual light produced by bioluminescent organisms is entirely harmless, but their presence may indicate an unhealthy marine ecosystem.

A bloom of glowing algae indicates low levels of oxygen in the water and higher levels of phosphorus and nitrogen. These conditions are far from ideal for the fish and have a devastating impact on the food chain.

How Long Does Bioluminescence Water Last?

Despite studying red tide trends for over 100 years, scientists are still no closer to understanding or predicting the phenomenon.

Research biologist Michael Latz of the Scripps Institution of Oceanography says, “We can’t predict when they are going to occur or long they will last.”

How Long Does Bioluminescence Water Last?

In 2018, a red tide lit up the Pacific Ocean, giving the Californian surf an eerie beauty. It didn’t last long, however, and it was as though the event had never occurred in a matter of days.

The bioluminescent plankton returned the following year, this time hanging around for nearly two weeks. Then, in 2020, the sea sparkled for months.

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What is the Best Time to See Bioluminescence?

Bioluminescence is the ocean’s answer to Aurora Borealis but you’ve got a much better chance of seeing the sea sparkle than getting a glimpse of the Northern Lights.

Displays of bioluminescent waves might be challenging to predict, but they are by no means a once-in-a-lifetime event.

The best time to see bioluminescence is usually during spring or summer, although some places in the world enjoy these spectacular light displays throughout the year.

What is the Best Time to See Bioluminescence?

Florida’s Indian River Lagoon sees light-producing comb jellyfish flock to its shores in the winter months, while the summer months see the arrival of the bioluminescent plankton.

The weather also has an impact on the ocean’s natural light display. In years of a combination of warm weather and good rains, the chances of seeing that bioluminescent glow increase substantially.

Identifying the presence of bioluminescent water is only the first step in appreciating it.

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Arriving at the beach during a full moon, for instance, will reduce your chances of a spectacular sighting as too much light from other sources makes it more difficult to see the bioluminescent glow.

Arriving at the beach before the moon rises give you the best chance of witnessing bioluminescence, especially if you manage to find a location with minimal light pollution.

Experts at Scripps Institution of Oceanography also say, “Bioluminescent displays are viewed best from a dark beach at least two hours after sunset.”

World’s Best Places to See Bioluminescence Water

Bioluminescent water is a natural phenomenon that occurs in all the world’s oceans in one form or another.

But if you want to witness the sea sparkle, you need to put the following destinations on your bucket list.

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World's Best Places to See Bioluminescence Water

#1 Mosquito Bay, Puerto Rico

The world’s brightest bioluminescent bay is situated on the magical Vieques Island in Puerto Rico.

The creatures responsible for this ethereal light are microscopic dinoflagellates known as Pyrodinium bahamense. Sometimes referred to as ‘whirling fire,’ these bioluminescent creatures respond to movements in the water by flashing a blue-green light.

The bioluminescence at Mosquito Bay is so bright because of the dense population of bioluminescent dinoflagellates. Up to 700,000 of these tiny organisms are within each gallon of water, all shimmering away.

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Although bioluminescence is visible in Mosquito Bay throughout the year, the best time to see this phenomenon is during the dry season. Between December and April, minimal cloud cover obscures your view.

On a dark, moonless night, it can be a vibrant and breath-taking experience.

Mosquito Bay, Puerto Rico

A narrow entrance to the bay effectively traps the dinoflagellates in Mosquito Bay which they’re perfectly happy with as the surrounding mangroves provide a constant source of food for the little critters.

Before you start imagining yourself swimming among the glittering organisms, think again. No swimming is allowed in Mosquito Bay as contaminants on the human skin may disrupt the ecosystem’s delicate balance.

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If you want to swim with bioluminescent organisms, you’ll need to head over to the mainland and visit Laguna Grande in Fajardo instead.

#2 Indian River Lagoon, Florida

During the summer months, the waters of the Indian River Lagoon are lit up with otherworldly blue glow lights, turning it into a breath-taking natural wonder.

At other times of the year, the bioluminescent comb jellyfish move in, creating a glittering rainbow of color.

Although the two experiences sound very similar, people who’ve witnessed them say there is no comparison between the two.

Indian River Lagoon, Florida

The most popular time to visit Indian River Lagoon is in the summer when the dinoflagellates are in full glow. However, when the comb jellyfish move in in the cooler months, the glow becomes multi-colored thanks to the jellyfish’s cilia.

Cilia are small hairlike structures that move in undulating waves. When the jellyfish produces its blue-green light, the cilia refract it, producing a rainbow of glittering lights.

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Whether you visit the lagoon in the summer or winter, keep an eye on the lunar cycles before booking a trip to see the bioluminescence water.

Dark nights when the new moon is just emerging will give you a much better view of this beautiful phenomenon after which, you’ll fully understand why the locals refer to it as “fire water.”

#3 Toyama Bay, Japan

Every April, Toyama Bay is lit up like a Christmas tree but not because of the presence of either dinoflagellates or bioluminescent comb jellyfish. Instead, the beautiful phenomenon along the coast of Toyama Bay is produced by tens of thousands of firefly squid.

Firefly squid, also known as sparkling enope squid or Hotaru-ika, grow to just 3 inches in length but produce a dazzling show to give most firework displays a run for their money.

Toyama Bay, Japan

This light display is only visible between March and April when the female squids rise to the surface to spawn. This is the last period of their lives, most of which is spent hidden in the ocean’s depths.

After spawning, the female firefly squids wash ashore exhausted by their ventures. Here, they are scooped up in their thousands and quickly converted from light display to sashimi or sushi.

Visitors flock to Toyama Bay to see the dazzling light show and enjoy the tasty creatures responsible for it.

#4 Mission Bay, San Diego

While Mosquito Bay enjoys bioluminescence every year, it’s a bit more hit and miss in San Diego where the presence of bioluminescent algae can change dramatically from one day to the next.

The dinoflagellates responsible for the sparkling waters in San Diego only light up when they have enough nutrients to sustain and stimulate them.

Mission Bay, San Diego

When a red tide pulls in, it brings an abundance of food, causing the population of bioluminescent creatures to explode.

Bioluminescent water only occurs in San Diego every few years, often during hurricane season. So to get the best view of this natural phenomenon, you want to find a dark, isolated beach with as little light pollution as possible.

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It’s also a good idea to avoid the full moon as the amount of light it produces can make it harder to see the blue light emanating from the ocean.

Some of the best sightings of 2022 were captured on Black’s Beach where dolphins illuminated by the neon blue light were filmed leaping through the waves.

#5 Jervis Bay, Australia

The Pyrodinium bahamense might be responsible for lighting up Mosquito Bay, but in Australia, there’s a different type of bioluminescent organism doing the same job.

During the summer months, Noctiluca bioluminescent dinoflagellates, or sea sparkles as they’re also known, collect in such large numbers that form a red tide on the water’s surface.

Sometimes this haze is so thick, that the bottom of the sea is completely obscured.

Jervis Bay, Australia

When night falls, this red haze comes to life, flashing blue lights from their tiny bodies the moment they’re disturbed.

These tiny organisms are protected against the wind and tides, close to the sheltered beaches of Jervis Bay and accumulate in their millions.

Noctiluca are so small that thousands of them can fit into a single drop of water. Therefore, the natural wonder witnessed at Jervis Bay is the work of millions of tiny critters.

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Quite why some marine creatures emit these bright lights remains something of a mystery, although scientists suspect that, in the case of the Noctiluca, it’s intended to either “startle or scare away its predators.”

Whatever the reason, the outcome is an unforgettable experience for anyone lucky enough to witness it.

#6 Halong Bay, Vietnam

Even without bioluminescence, Halong Bay is a place of incredible natural beauty. Giant limestone mountains rise up from emerald waters, creating a world of ethereal charm.

When the clear waters shimmer with glowing plankton, however, Halong Bay is transformed into a breath-taking paradise.

Halong Bay, Vietnam

It’s not easy to see the bright lights of Halong Bay while there are still boats in the water, but if you head down to the beach late at night, you’re in for a bucket list experience.

People who’ve experienced the phenomenon say it’s like “swimming in stars” or “diving into the world of Avatar.”

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You can see bioluminescence in Halong Bay throughout the year but the best time to catch it is when the moon is low and the water is calm.

That means avoiding the rainy season which takes place between July and September every year.

During that period, the high chance of storms and typhoons could ruin your chances of soaking up the bioluminescent light.


Some years ago, I was lucky enough to splash through the glowing ocean water at night while on holiday in Mozambique. It was a slightly surreal yet unforgettable experience that I would highly recommend.

Bioluminescence is a natural phenomenon that can transform our coastline into a spectacular display of color and light.

It can, theoretically, occur almost anywhere, but the places listed here are some of the best places to see bioluminescence water.

Bioluminescence is a natural phenomenon

Your chances of experiencing a bioluminescent event are increasing, as scientists have noticed a correlation between ocean acidification and bioluminescence.

Last year, a presentation at the annual Society for Integrative and Comparative Biology conference revealed that “when the ocean is more acid, bioluminescence is brighter.”

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Although ocean acidification isn’t a good thing for our oceans or our planet, the fact that it increases your chances of experiencing a sparkly ocean means there’s at least one silver lining… or should that be neon blue?

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