Bioluminescence Calendar: Best Nights in Costa Rica
Bioluminescence is best seen on dark nights, when there is little or no moonlight. Use this calendar to plan your private bioluminescence tour from Tambor Bay, near Santa Teresa and Montezuma. Dark blue days are the darkest nights, when the water glows the brightest.
Upcoming bioluminescence windows
- Oct 28 – Nov 13, 2026Darkest: Nov 6 – Nov 12
- Nov 27 – Dec 13, 2026Darkest: Dec 5 – Dec 11
- Dec 26 – Jan 12, 2027Darkest: Jan 4 – Jan 10
- Jan 25 – Feb 10, 2027Darkest: Feb 3 – Feb 9
- Feb 23 – Mar 12, 2027Darkest: Mar 5 – Mar 11
- Mar 25 – Apr 10, 2027Darkest: Apr 3 – Apr 9
- Apr 23 – May 9, 2027Darkest: May 3 – May 9
Why does the moon matter?
Bioluminescent plankton glow when the water moves, but their light is soft. A bright moon makes the glow hard to see. That’s why we only run this tour from a few days after the full moon until the new moon is about a quarter full. On those nights the sky is dark and every splash lights up.
Our private bioluminescence tour
Your group gets the whole boat, up to 14 guests, with a local captain. Choose between two departures: 12:30 pm (Tortuga Island + bioluminescence) or 4:30 pm (bioluminescence only). Both return around 7 pm. Boat tours depart from the Yacht Club in Tambor Bay, about 30 minutes from Santa Teresa, and hotel pick-up can be added.
Bioluminescence FAQ
Is bioluminescence guaranteed?
It’s a natural event, so the intensity changes from night to night. Choosing a dark-moon night gives you the best chance to see it.
Can we swim in it?
Yes. Swimming in the glowing water is the highlight of the tour.
What should we bring?
Swimwear, a towel and a change of clothes. Sunscreen and insect repellent are fine — they don’t affect the glow.
What if it rains?
Light rain doesn’t affect the bioluminescence — you can still see the glow and swim in it. Only very heavy rain makes it harder to see. If a strong storm is expected, we’ll contact you to move your tour to another dark-moon night.