The Ostional National Wildlife Refuge is located on Costa Rica’s Nicoya Peninsula. It is one of the most important nesting beaches in the world for the Olive Ridley sea turtle (Lepidochelys olivacea). Taking an Ostional tour is an exceptional opportunity. It lets you witness the extraordinary phenomenon known as the arribada (Spanish for “arrival”). During this event, tens of thousands of turtles come ashore at the same time to nest.

This event is so unique. Ostional tour is one of just a handful of beaches worldwide where it occurs. This makes it a bucket-list experience for wildlife enthusiasts.

🌍 What Makes Ostional Special

• Global Importance: Ostional is the second largest Olive Ridley nesting site in the world, after Playa La Escobilla in Mexico.
• Conservation & Community: Unlike most turtle nesting beaches, the Ostional community has a special government agreement. It allows them to sustainably harvest a portion of the eggs during the first days of nesting. This long-standing practice both supports local families and helps protect the turtles by reducing illegal poaching.
• Guided Visits Only: Access to the beach is only allowed with certified local guides. This ensures protection of the turtles and their habitat.

📅 Turtle Nesting Seasons at Ostional

• Year-Round Nesting: Olive Ridley turtles arrive at Ostional every month of the year, so visitors usually have a chance to see turtles nesting, regardless of the season.
• Peak Arribada Season (July – December):
  • This is the most spectacular time to visit.
  • Arribadas usually happen just before the new moon, when the nights are darkest.
  • The mass nesting event can last between 3 to 10 days.
  • During peak months, hundreds of thousands of turtles may arrive over the course of a single week.
• Smaller Arribadas (January – June):
  • Fewer turtles compared to the rainy season, but still impressive.
  • Good chance to see nesting, especially around new moon dates.

🌙 What to Expect on the Tour

• Evening or Early Morning Tours: Most tours happen at night (when the turtles come ashore) or at dawn (when late nesters can still be seen).
• Guided Experience: Local naturalist guides explain turtle behavior, nesting cycles, and conservation efforts.
• Possible Sightings:
  • Turtles crawling ashore
  • Nest digging and egg laying
  • Covering the nest and returning to the sea
  • Hatchlings emerging (if you visit during hatching periods, about 45–60 days later)

📝 Visitor Tips

• Respect the rules: No flashlights, camera flashes, or loud noises that could disturb the turtles.
• Best chance to see an arribada: Check moon phases (new moon is ideal) and plan for September–November if you want to witness the largest gatherings.
• Bring: Comfortable walking shoes, dark clothing, insect repellent, and lots of patience — nature runs on its own schedule.

📅 Ostional Turtle Nesting Calendar

Important note: Olive Ridley turtles nest year-round at Ostional, but the size of the arribadas (mass nesting events) changes with the seasons. Arribadas usually start a few days before the new moon.

🌱 Dry Season (January – April)

• January & February: Smaller arribadas, but still a good chance to see dozens or even hundreds of turtles on nesting nights.
• March & April: The driest months. Arribadas are less predictable and generally smaller. Visitors may see only a few dozen to a few hundred turtles per night.

👉 Good for travelers who want calmer beaches, but turtle numbers are modest.

🌦 Transition Months (May & June)

• Rain begins to return, improving conditions for turtles.
• Arribadas start increasing in size, sometimes reaching thousands of turtles.
• Not yet the peak season, but activity is more consistent than in the driest months.

👉 A nice balance: fewer tourists than peak rainy season, but growing turtle numbers.

🌧 Peak Rainy Season (July – December)

This is the best time to visit Ostional if you want to witness the largest arribadas.

• July & August: Big increase in turtle arrivals. Arribadas can involve thousands to tens of thousands of turtles.
• September, October, November: Peak nesting season. These months host the largest arribadas, sometimes with 100,000+ turtles arriving over several days. Beaches can literally be covered with turtles.
• December: Still very strong activity, though sometimes slightly less than the September–November peak.

👉 If you want to guarantee seeing turtles in mass numbers, visit between September and November near the new moon.

🐣 Hatching Season

• Turtle eggs incubate for 45–60 days, so hatching often overlaps with nesting.
• Visitors who are lucky may see baby turtles emerging and making their way to the ocean, especially if they visit about six weeks after a big arribada.

✅ Summary at a Glance

• Best months: September – November (largest arribadas).
• Good months: July, August, December (big but slightly smaller arribadas).
• Moderate months: May, June, January, February (smaller, but still nesting).
• Least predictable: March, April (smallest arribadas, dry season).

✨ Why Visit?

The Ostional Turtle Tour is more than just wildlife watching — it’s an educational and cultural experience. You’ll be supporting community-based conservation while witnessing one of the most extraordinary natural spectacles on Earth.