If you’ve ever seen ocean waters or bays glowing brightly at night, you might have witnessed bioluminescence, a natural phenomenon where underwater organisms emit light through a chemical reaction.
The sight can seem almost otherworldly, and you’ll find it around the globe in places from California to Japan. Some require a guided kayak or boat tour, while others can be seen from shore for free. But there’s more to spotting this wonder than simply showing up after dark.
The science behind the glow varies from place to place, and these natural light shows are best experienced around the new moon. In some destinations, microscopic, single-celled organisms known as dinoflagellates flash blue when waves or paddles disturb the water. Elsewhere, 3-inch long firefly squid that typically live in the deep ocean come to the surface to spawn and feed, and create entirely different displays.
The tricky part is getting the timeline right. While I've been to Puerto Rico in search of these mesmerizing displays, I've yet to witness the flashes of light in person. However, if you target the following locations at the correct times, you’ll likely have better luck than me. Here’s where to start.
In this article
Indian River Lagoon, Florida
Water sports in Florida can be a fun activity to add to your must-do list, but you might want to consider booking your kayaking excursion for the evening hours for an extra-special experience.
If the conditions are right, your tour of the Indian River Lagoon near Titusville can include a glimpse of bioluminescent dinoflagellates, with comb jellies sometimes adding another glow-in-the-dark surprise. The dinoflagellates flash blue-green when the water is disturbed, while comb jellies are transparent animals whose rows of tiny cilia can produce a shimmering, rainbow-like effect.
Summer is generally the strongest window for the lagoon, with July through September particularly popular for night paddles, although conditions can vary. The water needs to be warm enough to encourage growth of these microorganisms, and rainwater can dilute the effects of bioluminescence, providing less ideal viewing conditions.
Swimming isn't recommended, so the best way to experience the lagoon is on an organized paddling tour with outfitters such as Florida Adventurer and A Day Away Kayak Tours. For the best experience, book a night with no moon so you don't have its light dampening the faint glow of the microorganisms.
Mosquito Bay, Vieques, Puerto Rico
Puerto Rico is home to three bioluminescent bays, including Mosquito Bay, which is located on the island of Vieques, off the eastern coast of Puerto Rico in the Caribbean Sea.
Here, you’ll find exceptionally bright displays of dinoflagellates called Pyrodinium bahamense, which is a microscopic form of marine algae that flashes electric blue when disturbed by paddles, fish, or waves.
The shallow water, narrow opening to the ocean, and mangrove forests of Puerto Rico's bioluminescent bays trap the organisms and create an ideal ecosystem for them to thrive. And unlike other locations, it may be viewed here year-round, though heavy rains and storms can disrupt the ecosystem and reduce water clarity.
Swimming isn't permitted, so you'll need to book a kayaking excursion with Mosquito Bio Bay Tours or another outfitter. Choose an early tour time if you plan to return to the mainland, or make arrangements to stay overnight on Vieques.
The other two bays are Laguna Grande and La Parguera. Laguna Grande in Fajardo is the closest to San Juan, making it the easiest option for visitors who don’t want to book a separate overnight stay. The blue glow is not typically as bright as what you’ll see in Mosquito Bay, but kayaking tours are available.
And located in the southwestern portion of Puerto Rico, La Parguera is the only bioluminescent bay in Puerto Rico where swimming is permitted. While the blue-green glow is also typically dimmer than Mosquito Bay (due to water disruption from boats), some visitors might prefer the opportunity to swim with these amazing microscopic creatures.
San Diego, California
San Diego has miles of beautiful beaches, but head to those in La Jolla Shores, Torrey Pines State Beach, and Black's Beach after dark, and you might catch a glimpse of nighttime waves glowing blue.
Here, the color comes from bioluminescent dinoflagellates, particularly Lingulalax polyedra. When concentrations of these microscopic organisms build into a red tide (an overbloom that makes the water appear red during the daytime), waves and moving water can trigger an electric blue glow. This makes their timing less predictable. While scientists have documented an increase in these red tides, you may only have a few days each year when conditions are right for viewing.
Usually, these large dinoflagellate blooms will form from spring through fall, but individual red tides can last from days to weeks or longer.
Viewing is best done from a dark beach at least 2 hours after sunset. There's no admission fee or registration required, as California beaches are public, but you will require a lot of luck to spot this natural phenomenon.
Toyama Bay, Japan
Toyama Bay is on Japan's main island of Honshu, along the Sea of Japan. Visitors can reach the bay via high-speed train from Tokyo in about 2 hours. Toyama Bay offers one of the world's more unusual bioluminescent experiences because the stars of the show aren't plankton—they're tiny firefly squid (hotaru-ika).
These squid have light-producing organs called photophores and rise to the surface in spring, creating flashes of blue light as they gather in the bay in search of mates.
March through June is the official tourism season, however, the organized Firefly Squid Sea Tourism boat operates during a shorter spring window to offer the best opportunity of viewing this phenomenon. Visitors board before dawn at the Hotaruika Museum for a frigid boat trip into the bay. Because space is limited and the season is short, booking well in advance is highly recommended.
The museum is also worth visiting on its own to learn about these and other bioluminescent creatures through interactive exhibits and touch pools.
Bellingham, Washington
Just south of Bellingham, the Salish Sea comes alive each summer with nighttime flashes of neon blue.
The color comes from microscopic marine plankton, which emits brief bursts of blue-green light when the water is disturbed. The best time to see them is typically June through September, especially around the darkest nights near the new moon.
Guided kayak and stand-up paddleboard tours launch from Larrabee State Park, making it easy to experience the wonder without navigating the shoreline after dark, as swimming is not recommended. Know that launching from this area is limited to tours with after-hours permits, as the park closes at dusk to the public.
If you’d prefer a DIY experience, the Community Boating Center boat launch in Fairhaven comes recommended as a spot with 24-hour access for those looking to set out on kayaks or paddleboards on their own.
The Shortcut
Florida and Puerto Rico offer some of the most reliable paddling experiences, with bright dinoflagellate displays and guided nighttime tours, and the latter offering visibility year-round.
San Diego is the wild card, where bioluminescent red tides can create glowing waves, while Japan’s Toyama Bay puts a different spin on bioluminescence with tiny firefly squid lighting up the water during their spring migration.
Timing matters wherever you go, with dark, moonless nights offering the best conditions.
