Visit the Bio Bay on Foot at Las Cabezas Nature Reserve

Update 1/2022 Las Cabezas has reopened for tours, but it looks like their new night time tour is very different…doesn’t seem to go to the biobay area or the lighthouse. .

Laguna Grande at Night

The bioluminescent lagoons in Puerto Rico are natural wonders that I think everyone who visits the island should see. There are 3 lagoons that have bioluminescent properties all year ’round – the one in La Parguera in Lajas, Mosquito Bay on Vieques and Laguna Grande in Fajardo. Until recently, the only way to access any of these biobays was either kayak into them or go aboard a boat. But now there is another alternative! The Fideicomiso de Conservación de Puerto Rico (Conservation Trust of Puerto Rico) now offers night-time walking tours of Las Cabezas Nature Reserve and Laguna Grande.

The Tour

This night tour is relatively new and unpublicized. We were surprised to find that we were the only people going on the tour that night, so we had a private tour with our guide Pedro. You ride in a tram car as the guide explains the reserve and it’s ecological importance to Puerto Rico. He also tells you about the night-sounds you are hearing, like the 3 types of coqui frogs they have at the reserve and their different calls.

Our first stop was the beach. Pedro discussed the importance of the area for the endangered sea turtle nesting. He also discussed the light pollution that interferes with the hatchling turtles’ ability to make it from their nests to the open sea – they get confused as to which way it is to the water. Pedro was very knowledgeable about the 4 different turtles that nest in the area and even drew, in the sand, the different patterns that each turtle makes when walking across the sand.

After that, we walked across the road to the Laguna Grande, where he told us about the animals and birds that you will see and hear at night. He said there is this big bat that catches fish in the lagoon. I’m really glad we didn’t see any of those!

After that stop, it was back on the tram for the ride up to the lighthouse. We stopped once along the way to look at the land crabs. They are nocturnal and dig holes in the sand to hide in. Pedro told us about the land crabs and how the return to the sea to lay their eggs. He also told us about how his father used to catch the land crabs with his hands. Maybe he didn’t notice, but they have big pinching claws!

To The Lighthouse

After our short encounter with the land crabs, we headed up to the light house.

Fajardo Lighthouse - Faro de Fajardo

Built by the Spanish in 1880, the lighthouse (El Faro del Fajardo) has been restored to it’s former glory. I have been to this lighthouse during the day, but this was the first time someone actually pointed out the importance of the lighthouses. There are 2 wall-charts on the ground floor of the lighthouse that I found extremely interesting. One shows the location and range of all the lighthouses on Puerto Rico. The other shows the different patterns of light each light house makes. So boaters could tell where they are at night, just by watching the pattern of the light. Really smart!

After talking about lighthouses, you watch a short (maybe 10-minute) Powerpoint presentation about the organisms (Pyrodinium bahamense) that cause the water to glow. They are called dinoflagellates. It was educational and interesting.

The problem of light pollution was brought up again. Not only does it mess up the turtles, it also diminishes our ability to see the glowing of the bioluminescent dinoflagellates in the bay.

Light Pollution in Puerto Rico

After the presentation and discussion, you head up to the top of the lighthouse. Even at night, it is a great view! You can see the lighthouse in all it’s glory! You can also see the other out islands – Lobos, Vieques and Culebra. And when you look south-west toward the land, you can see ALL THE LIGHT. San Juan is just this huge glow to the right. Luquillo is lit up, too! Fajardo has made efforts to reduce the light, with yellow bulbs and they have blocked the light of the light house so it doesn’t hit land. It is amazing to see all this light and see how it ruins some of our enjoyment of nature. If you look up and out to sea, you can see a zillion stars. Pedro pointed out some of the constellations and planets for us. If you look over the land, you can barely see but a few stars. Light pollution is really a bigger problem than I realized.

Laguna Grande – The BioBay

When you are done enjoying the lighthouse, you get back on the tram and go to the bio bay. Here comes the fun part! You walk along a long boardwalk that winds through the mangrove swamp. Along the way, Pedro pointed out some of the mangrove bird sounds and the plants (we tasted the salt the black mangrove excretes from its leaves). Finally, the boardwalk enters Laguna Grande. They have long sticks there that you can use to splash the water. Using the sticks you can smack, stir and generally play around with the water. Pedro showed us how to scare the fish. When they swim away, they leave trails of light behind them. We walked along the boardwalk and tried the water in many different areas since some areas glow more than others, depending on the concentration of the dinoflagellates. We were able to play out there for about 20 minutes or so. It was really neat – like drawing in the water with light.

This is a great way for people who can’t kayak to experience the biobay in Fajardo. And, it also is affordable.

Reservations & Other Details

They run these night tours only Thursday, Friday & Saturday nights. You MUST make reservations for this tour and you need to specify what language you would like it in (English or Spanish).

Admission: Individuals $24.00, students $14.00. You must pay when you make your reservation. They accept Visa, Master Card and American Express. Reservation are needed- use the website to order tickets for the date you want in the language you want.

You can visit their web site for reservations Go to their website for more information.

Tours start at 7:00pm and are approximately 2 hours long.

You do want to make sure you do this tour when the moon is not too bright. You can check our biobay/moon calendar to make sure the moon is favorable for viewing on the night you want to go.

This is a moonlit tour. Bring a small flash light if you have one. It isn’t too hard to see where you are going in the dark, since there are so many stars (and light pollution!). The guide has a flash light for the really dark areas. Most of this tour is handicapped accessible. Wear comfortable shoes or sneakers since you will be walking on a boardwalk and a few steps in some moist sand/muddy areas.

Call for more info. (787)- 722-5882

You must get a reservation number in order to ensure that you have a reservation (don’t just leave a phone message and assume you have a reservation – you’ll be sadly mistaken). For the best way- Reserve On-Line at their webpage and print out your confirmation.

Please refer to our article on the daytime tour at Las Cabezas for driving directions.

Click on a placename below to view the location on Google Maps ... assumes no responsibility regarding your safety when participating in the activities described in this article. Please use common sense! If your mother or that little voice in your head tells you that you are about to do something stupid … then don't do it! Read more about Safety →

Ads & Sponsors

Other Puerto Rico Resources …

Coqui's Hideaway Rainforest Villa in Rio Grande Located in the Foothills of El Yunque