Best time of the month to visit the Bioluminescent Bay in Vieques

Best time of the month to visit the Bioluminescent Bay in Vieques

By Stephanie Velazquez

When you visit Puerto Rico, the number 1 must do is to experience the world’s brightest bioluminescent bay called Puerto Mosquito (Mosquito Bay), which is located in Vieques island. Puerto Mosquito has bioluminescence year-round. To such a famous tour, well known to many, and recognized by the Guinness Book of World Records, you probably would appreciate knowing when the best time to experience such beauty from nature would be. Especially if you are traveling from overseas. 

The Bio Bay is closed during full moon

The Departamento de Recursos Naturales y Ambientales (The Department of Natural Resources), DRNA, has restricted tour companies to operate during the night before full moon, the night of, and the night after full moon since these three nights are when the moon is at its brightest. The reasoning behind their decision is to let the micro-organisms in the water responsible for the bioluminescence have a rest from human contact for at least three days of each month since our visibility of the glow in the water is less than usual. When there is a full moon, what we notice is an intense reflection of the moon on the surface of the water, while the water glows back at you when it's agitated, making the viewing of the bioluminescence to our sight barely noticeable.


Moon phases diagram. 

Understanding the moon

The visibility of the moon is different to us every day. It all has to do with the angle at which we are able to see it. The angle of sunlight changes, making our view of the moon seem different. The moon has phases because it has spheres and it orbits the earth, so the angle on which we see it changes. Therefore, the shape or phase of the moon depends on where it is on its orbit around earth. A month from now, you will see the same phase again as it goes from the new moon, waxing crescent, first quarter, waxing gibbous, full moon, waning gibbous, last quarter waning crescent, and it goes all over again.

The best night to experience Puerto Mosquito 

The full moon is arguably the most gratifying object in the sky, but in this case, you would want to schedule your trip around the moon. One thing to keep in mind is that the intensity of the bioluminescence that we experience at the bio bay is not something humans can control. Understanding the moon phases, knowing how environmental factors and elements have played a role in the past causing both positive and/or negative outcomes, we are now able to understand and better predict how the viewing experience during the night time tour at the bay will be. This being said, understanding the moon phases is very important because the phases happen every month over and over again.

The new moon is the first lunar phase. It is when the sun and the moon have the same ecliptic longitude. The lunar disk is not visible to us, therefore we cannot notice the moon in the sky causing the new moon to be the darkest night of the month, which would make this the best night to experience the bioluminescence in Puerto Mosquito (Mosquito Bay). 

Dates we will have new moon (the most ideal night/ darkest) in 2023:

January 21st

February 20th

March 21st 

April 19th

May 19th

June 17th

July 17th

August 16th

September 14th

October 14th

November 13th

December 12th

Adding on, if you had already planned your vacation and didn't consider the moon phases, don’t worry, your trip is not ruined. After all, Puerto Mosquito is the brightest bioluminescent bay in the world! Even when the moon is in the sky, we are able to still appreciate bioluminescence. Following the full moon, we will notice the moon rising an hour after each night. In some cases, it is best to schedule your tour for the first time slot, before the moon rises. If you are unsure, ask a booking representative and they will be happy to help you schedule your trip for the best time.

 Dates the bio bay will be closed in 2023:

January: 5, 6, 7

February: 4, 5, 6

March: 6, 7, 8

April: 5, 6, 7

May: 4, 5, 6

June: 3, 4, 5

July: 2, 3, 4, 31

August: 1, 2, 30, 31

September: 1, 28, 29, 30

October: 27, 28, 29

November: 26, 27, 28

December: 26, 27, 28

Tell us how your planning is going, do you have any questions?