The Ostional arribada is a mass nesting of olive ridley sea turtles at Ostional National Wildlife Refuge, about 15 minutes north of Nosara on Costa Rica’s Nicoya Peninsula. Arribadas happen roughly once a month, but the big ones come in the rainy season, especially September to November, when more than 100,000 turtles can come ashore in a single night. To see one, you need a certified local guide, and you should plan to stay a few nights near Ostional, since the exact dates shift.
This guide is for travelers who want to see an arribada in person. It explains what happens, when to go, how to book a guide, how to get there and the rules on the beach.
| Ostional arribada | At a glance |
|---|---|
| Species | Olive ridley sea turtles |
| Where | Ostional National Wildlife Refuge, Nicoya Peninsula, Guanacaste |
| Best months | September to November; smaller events the rest of the year |
| Timing | Roughly monthly, often around the last quarter moon |
| Guide | Required; groups capped at nine visitors |
| Getting there | About 15 minutes from Nosara, 2 hours 15 minutes from Liberia |
| Hatchlings | About 45–50 days after nesting |
The basics
What Is the Ostional Arribada?
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Arribada means “arrival” in Spanish. Instead of nesting one at a time, thousands of female olive ridleys gather offshore and come ashore together over several days to dig nests and lay about 100 eggs each. Ostional is one of the few beaches anywhere where this happens on a large scale.
Costa Rica has one other arribada beach, Playa Nancite in Santa Rosa National Park, but it’s a protected research beach that isn’t open to tourists. That makes Ostional the place to see one.
Timing
When to See an Arribada at Ostional
- Peak season: the biggest arribadas happen from about September to November, in the rainy season. Then, more than 100,000 turtles can come ashore in a single night, and an event can last up to two weeks.
- Rest of the year: smaller arribadas happen in the dry season, often with fewer than 20,000 turtles over three or four nights.
- Moon phase: arribadas tend to start around the last quarter moon, in the darker nights before the new moon, but they can begin a couple of days early or late.
- Time of day: most nesting happens at night, but during big events you can see turtles on the beach in daylight too.
Because the dates aren’t predictable, book two or three nights nearby and stay flexible. Check with the local guide association before you drive in. For other turtle beaches and seasons, see our guide to sea turtle nesting sites in Costa Rica.
Visiting
How to Visit Ostional
Book a certified local guide
During an arribada, the beach is closed to anyone without a certified local guide, and rangers turn away visitors who arrive alone. Groups are capped at nine people. Book with the guide association office in Ostional or through its Facebook page; fees are modest, around $10 to $20 per adult in recent years, so confirm the current rate when you book. Tours often run around dawn and late afternoon, and guides adjust to the turtles. Tour companies in Tamarindo and Playas del Coco also run day trips.
Getting to Ostional
Ostional is about 15 minutes by road from Nosara, about 2 hours 15 minutes from Liberia airport and 4.5 to 5 hours from San José. The last stretch is unpaved, and a bridge now crosses the last river from the north. A high-clearance car is fine in the dry season, but a 4×4 is the safer choice in the rainy season, when the road gets muddy. Avoid driving the dirt roads after dark. See our Costa Rica car rental guide.
Where to stay
Ostional village has a few small lodges and cabinas within walking distance of the beach, which is handy for night and early-morning visits. For more choice, stay in Nosara, 15 minutes away, or in Sámara, about an hour south. A day trip from Tamarindo is possible but leaves less flexibility for timing.
Rules
Beach Rules During an Arribada
- Don’t pick up hatchlings or carry them to the water; let them crawl on their own.
- Watch your step. The sand is full of nests, and turtles may be digging around you.
- Keep belongings secure. Keys and phones are easy to lose in the sand.
Conservation
The Ostional Egg Harvest: Why It’s Legal
During a big arribada, later turtles dig up and destroy many of the nests laid earlier. For more than three decades, Ostional has run one of the few legal sea turtle egg harvests anywhere. When about 1,000 turtles have come ashore, the local development association, ADIO, can declare a harvestable arribada, and community members may collect a regulated share of eggs in the first days only. In return, the community patrols the beach, clears debris and guards against poachers.
The refuge covers about 16 km (10 miles) of coast, including Ostional, Pelada, Guiones and Nosara beaches, and park guards patrol it daily.
Hatchlings
When Do the Hatchlings Emerge?
Olive ridley eggs hatch about 45 to 50 days after they’re laid, so hatchlings from the big September to November arribadas emerge from about October to February. Early morning is the best time to see them heading for the sea, when vultures and other predators are waiting too.
See what else is active that season in our month-by-month wildlife calendar, and plan around the weather with the best time to visit Costa Rica by region.
FAQ
Ostional Arribada: FAQ
When is the best time to see the Ostional arribada?
September to November, when the largest arribadas happen. Smaller events occur through the rest of the year.
How often do arribadas happen?
Roughly once a month, often around the last quarter moon, though the exact start can shift by a few days.
Do I need a guide at Ostional?
Yes. During an arribada, only visitors with a certified local guide may enter the beach, in groups of up to nine.
How much does an Ostional turtle tour cost?
Local guide fees have been around $10 to $20 per adult in recent years. Day trips from Tamarindo or Playas del Coco cost more. Confirm current prices when you book.
Can I see the arribada during the day?
Most nesting is at night, but during big arribadas turtles can be on the beach in daylight too.
Why are people allowed to collect eggs at Ostional?
Later turtles destroy many early nests, so a regulated community harvest in the first days of an arribada is allowed in exchange for beach patrols and protection.
The short version
Go between September and November, and stay a few nights near Ostional.
Book a certified local guide; you can’t go on the beach alone.
No flash, no white lights, dark clothes, and let the hatchlings crawl.