Bioluminescence in Tomales Bay: Everything You Need to Know

Imagine floating under a sea of stars, atop the calm waters of Tomales Bay. As your kayak curves through the water, the surface begins to sparkle with white-blue light as the boat and paddle disrupt the stillness. This otherworldly experience – often called the Northern Lights of the Sea – is due to the presence of bioluminescent microorganisms, which turn Tomales Bay into a glittering natural wonderland when the conditions are just right. 

While bioluminescence isn’t unique to Tomales Bay, this pristine natural haven in Point Reyes National Shoreline is considered one of the best places in North America to experience it. Scientists, nature lovers and kayakers flock to the area to witness this incredible sight firsthand. But although bioluminescence in Tomales Bay occurs regularly, there are some important things to know before you go. Read on to discover everything you need to know to make the most of this unforgettable experience.

What Causes Bioluminescence in Tomales Bay?

The marine bioluminescence in Tomales Bay, California, is primarily caused by tiny organisms known as dinoflagellates. These single-celled creatures emit a glow when disturbed or agitated. Although other types of marine life are also bioluminescent, dinoflagellates are often the culprit for making sea waters sparkle. Bioluminescent events commonly follow "red tides" which are large algae blooms. The dinoflagellates are thought to feed on algae, which may be why bioluminescence often corresponds with algae blooms.

When Can You See Bioluminescence in Tomales Bay?

Bioluminescence in Tomales Bay can occur year-round but it occurs most prominently in summer. The phenomenon is best observed during the dark of a still, moonless night. In Tomales Bay, this includes select nights from August through November, coinciding with neap tides. It is crucial to pay attention to the position and phase of the moon because bright moonlit nights will make it difficult to see the glow of bioluminescence. A night with calm waters and little wind is also preferred for experiencing the magic of this incredible natural phenomenon.

Where Does Bioluminescence Occur in Tomales Bay?

Dinoflagellates seem to amass in warmer, shallower, calm waters with proximity to deep water and they “eddy up” based on tidal flows. Find the darkest spots in the bay or wait until the moon has been down for a couple hours.   

Insider tip: We’ve had good luck experiencing bioluminescence in Tomales Bay along the western shoreline. During the darkest nights, plenty of bioluminescence can also be found on the west shore of Hog Island. Make sure to stay 300ft away from the rest of the island, including the north and east shoreline.  Try exploring the shallow shoal between the two channels north of the island. Look for spent, floating mass of eelgrass in the area.  

Be sure to avoid the gap between Duck Island and Hog Island.  It can get shallow and will put you within 300 feet of the harbor seals and brown pelicans.

Is it Safe to Swim in Bioluminescent Waters?

It is generally safe to swim in bioluminescent waters, including in Tomales Bay, but it is not safe to swim when algal red tides are present. So the question of safety depends on the present state of the water, what’s causing the bioluminescence, and can vary from location to location. In Tomales Bay, swimming is generally safe, although the water temperature is chilly year-round so common sense precautions should be taken, particularly at night.

What’s the Best Way to Experience Bioluminescence in Tomales Bay?

The only way to experience bioluminescence in Tomales Bay is via a kayak, because the phenomenon is not visible from shore. And the best way is by booking a guided bioluminescent kayak tour with an experienced guide and proper gear. A tour guarantees you the best experience because a guide who knows the Bay will not only be able to safely instruct you on nighttime kayaking but also lead you to the areas of the bay where you are most likely to experience bioluminescence. Even for experienced kayakers, paddling in the pitch dark along a rocky shoreline in a bay that experiences tidal swells and periodic high winds can be a dicey proposition. A tour allows you to maximize your time on the water, stay safe, and experience the magic of bioluminescence without having to manage the navigation and safety aspects on your own. 

Insider tip: Light pollution can impact sightings.  Make sure to wear a red light, avoid white lights, and explore areas far away from the light emanating from shore. Also, be advised that photographing the bioluminescence in Tomales Bay is near impossible from a kayak – the conditions require long exposures and a still platform, which is not possible from the water. 

What’s it Like to Experience Bioluminescence in Tomales Bay?

Experiencing bioluminescence by kayak in Tomales Bay is an unparalleled adventure inspiring awe, wonder, and often, even in groups of 10-12 paddlers - total silence. It leaves groups speechless. In addition to seeing bioluminescence, a nighttime kayaking tour is itself a physical and mental challenge. It’s dark. There is wildlife. There is often fog and your guide may be leading you via a compass. While it requires not only physical strength but also a touch of courage to get out on the water in the pitch black of night, the reward is immense. As the last of the daylight fades, your kayak begins to etch glowing trails on the water's surface. As you make your way across the channel, you are welcomed with a dazzling display of otherworldly beauty. 

For a tranquil half hour, you take shelter from the wind in the shadow of towering 30-foot cliffs along the shoreline. But you are far from alone. Enthralled by the bioluminescent display, you will watch guppies, shrimp, and larger creatures, including leopard sharks, swim through the radiant waters, stirring up clouds of luminescent bubbles. There is truly nothing else quite like it.

Ready to Book Your Tomales Bay Bioluminescent Adventure?

Experiencing bioluminescence in Tomales Bay is a bit like being dropped into the Milky Way – with glittering stars above and sparkling dinoflagellates below it’s a truly unique and breathtaking phenomenon. Booking a tour with an experienced guide will help you make the most of your time on the water, ensure your safety, and help supply the necessary gear and instruction for a flawless, totally enjoyable experience.

Here at Napa Valley Paddle, we’ve been facilitating tours and introducing people to the joy of bioluminescence on Tomales Bay for years. Our experienced guides will get you set up in a tandem kayak, provide all safety gear and instruction, and escort you through the dark of night to the best places in the bay to encounter bioluminescence. Discover more and book your tour here.