Things to Do in Fajardo

By daylight, Fajardo's bioluminescent lagoon appears just as scenic as any other bay on the tropical Puerto Rican coastline. But come nightfall, the Laguna Grande bio bay glows fluorescent with every movement and splash, thanks to the presence of microscopic plankton that thrive in the shallow Caribbean waters. Read on to learn how to take your own memorable Bio Bay tour.

The Basics

Bio bay tours allow visitors the chance to set the water aglow and create a trail of light with every stroke of a kayak paddle. To see the bioluminescence, night trips are offered around the cycles of the moon, with ideal timing on the darkest nights. These guided kayak tours are available departing from San Juan or Luquillo, which is only nine miles (15 kilometers) away. It’s common to couple kayaking with an afternoon nature walk to La Mina Falls in the nearby El Yunque National Forest.

What to Expect When Visiting the Bioluminescent Bay

Bio bay kayaking trips frequently set out in the early evening around sunset, launching from Las Croabas with a tour guide or instructor. These kayak tours travel through a dense collection of mangrove trees under a total canopy of darkness, and once you’re out of the mangrove tunnel, the stars above provide the only light by which to view the glowing waters, where the tips of your paddles will slowly begin to glow as they strike the liquid surface. There’s no swimming in the bay during this popular Puerto Rico vacation activity, but it’s easy to pass your hand through the water over the side of your kayak.

How to Get There

Laguna Grande is located in the Las Cabezas de San Juan Nature Reserve just off the shores of Fajardo, about 40 miles (65 kilometers) or an hour’s drive east of Old San Juan, a major tour departure point.

Why Does the Bio Bay Glow?

Although the glowing water often gives visitors a magical feeling, this spectacular natural wonder is actually caused by pyrodinium bahamense, single-celled organisms that glow when disturbed. The bay is surrounded by red mangrove trees, native to the surrounding El Yunque rainforest, that provide vitamin B12 to the marine plankton and create the perfect environment for their survival. There are only a handful of places in the world where this natural phenomenon is consistently found, two others of which are also on Puerto Rico, the Island of Enchantment: at Mosquito Bay on Vieques Island and the bay at La Parguera.