Skip to content
Bioluminescent BaysPuerto Rico

Choose the right Puerto Rico bioluminescent bay for your trip

The best time to go is within three days of a new moon. Puerto Rico has three bays: Mosquito Bay in Vieques is the brightest, Laguna Grande in Fajardo is the closest to San Juan, and La Parguera is the only one where you can swim.

Vieques · Fajardo · Lajas

A plankton net trailing through dark water behind a boat at La Parguera, the water around it glowing blue.
Plate 1a. A plankton net trailing behind a boat off La Parguera, 18 Jun 2024. 1/40 sec, f/1.4, ISO 32,000, edited. Far brighter than your eye will see it. Moon about 90% lit, 3 nights before full. Photo: NASA/Milan Loiacono
Mangrove cays in shallow blue water off La Parguera, seen from above under a gray sky.
Plate 1b. Mangrove cays, La Parguera, 26 Dec 2006, daytime. Photo: Hiram A. Gay, Public domain, cropped
A boat of OCEANOS interns collecting samples at La Parguera at dusk, with a lightning storm in the distance behind it.
Plate 1c. OCEANOS interns collecting plankton samples, with a lightning storm in the distance, La Parguera, 18 Jun 2024. No glow visible in this frame. 1/40 sec, f/1.4, ISO 32,000, edited. Moon about 90% lit, 3 nights before full. Photo: NASA/Milan Loiacono
18 operators compared
17 field guides
Operators checked 31 Oct 2026
Next new moon 8 Dec 2026

When to go

Go now, through 12 November

New moon on the 9th, Puerto Rico time. Full moon on the 24th, when the glow is barely there and Mosquito Bay closes.

Full calendar →

The field guide, by email

Plan the right bio bay experience.

Practical, researched tips on moon phases, the three bays, and tour options. No daily emails.

Optional. It helps us send what fits your trip.

Subscribe to occasional planning emails from Bioluminescent Bays PR. Unsubscribe anytime. Privacy policy.

Find the right bay

See which bay is brightest, closest, or the one you can swim in.

Book on the right night

Use the moon calendar to avoid washed-out tours.

Compare operators fast

Tour type, starting price, and trade-offs in one place.

The register

Three bays, and what separates them

They share one phenomenon and almost nothing else: the access rules, the brightness, and the trip each one demands are all different.

Puerto RicoViequesCulebraSan JuanMosquito BayLaguna GrandeLa Parguera
Plate 2. Map of Puerto Rico's bioluminescent bays: Mosquito Bay on Vieques, Laguna Grande in Fajardo, La Parguera in Lajas. Schematic. Each marker links to its bay entry, and each entry below links to Google Maps.
A mangrove channel at La Parguera by day.
Plate 5. La Parguera mangroves, 26 Dec 2006, daytime. Photo: Hiram A. Gay, Public domain

La Parguera

Where
Lajas
Getting there
About 2.5 hours from San Juan
On the water
Motorboat, kayak, or glass-bottom boat
Tours from
$22 glass-bottom boat. Swim tours from $40
Swimming
Yes on 7 of 8 operators, under your operator's briefing
Note
The only bay for swimming
Coords
17.9700° N, 67.0450° W
Map
La Parguera on Google Maps
Read the La Parguera entry →

Appendix A

18 operators, compared

Operators checked 31 Oct 2026
BayOperatorsAccessTours fromSwimming
Mosquito Bay4Kayak, electric boat$65No
Laguna Grande6Kayak, one electric boat$44 plus fees ($51.70 at checkout)No
La Parguera8Motorboat, kayak, or glass-bottom boat$22 glass-bottom boat. Swim tours from $40Yes on 7 of 8

Starting prices as listed by each operator, checked 31 Oct 2026. Some add tax or fees at checkout.

Compare all 18 operators →

Appendix B · Before you book

Questions about the bays

How many bioluminescent bays does Puerto Rico have?

Three: Mosquito Bay in Vieques, Laguna Grande in Fajardo, and La Parguera in Lajas. They share one phenomenon and differ in almost everything else: the access rules, the brightness, and how you get on the water.

What makes the water glow?

Bioluminescent plankton. The glow comes from a dinoflagellate called Pyrodinium bahamense, a single-celled organism that flashes when the water around it is disturbed. It is a defense reaction, which is why still water shows nothing and a paddle stroke lights up.

How the plankton work →

Which bay is closest to where I'm staying?

From San Juan and anywhere east of it, Laguna Grande in Fajardo, about 45 minutes by car. From the south or west coast, including Ponce, Rincon and Cabo Rojo, La Parguera in Lajas. Mosquito Bay is on Vieques and needs a ferry or flight whatever else you have booked.

Find your town →

Which of Puerto Rico's bioluminescent bays is the brightest?

Mosquito Bay on Vieques is the brightest of the three, and is often cited as the brightest bioluminescent bay in the world. It also takes the most planning to reach, since it sits on a separate island.

Read the Mosquito Bay entry →

When is the best time to see the bioluminescence?

Aim for a new moon, give or take about three nights, when the sky is darkest. The glow is there every night, but moonlight washes it out, so a dark sky is what separates a bright night from a disappointing one.

Check the moon calendar →

Do the bays glow during a full moon?

Barely. The bioluminescence is real every night, but a full moon drowns it out. Mosquito Bay in Vieques also closes around the full moon; Laguna Grande and La Parguera stay open but look much weaker.

Can you swim in the bioluminescent bays?

Only at La Parguera in Lajas, and only under your operator's briefing. Swimming is not allowed at Mosquito Bay or Laguna Grande, where tours run by kayak or electric boat.

Read the La Parguera entry →

How much does a bioluminescent bay tour cost?

Starting prices run from $22 to $85 per person across the 18 operators we list, as published by each operator and checked 31 Oct 2026. The price depends on the bay and on whether you go by kayak, electric boat, or motorboat, and some operators add tax or fees at checkout.

Compare all operators →

Still not sure which bay fits your trip?

Compare all 18 operators →View the moon calendar