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Ostional Sea Turtle Arribada Calendar and Night Walk Rules from Nosara
Just north of Nosara, Ostional Wildlife Refuge hosts one of the planet's largest olive ridley sea turtle mass nestings, called arribadas.
Direct answer: Olive ridley arribadas at Ostional, about 15 to 20 minutes north of Nosara, occur most often from roughly July to December, typically around the last quarter moon. Visitors must enter with a certified local guide, avoid flash and white lights, keep distance from nesting turtles and follow refuge rules.
What Is an Arribada?
During an arribada, thousands of olive ridley turtles come ashore over several days to nest. Ostional is one of only a few beaches worldwide where this happens regularly, and it is protected as a national wildlife refuge.
When to Go
Arribadas happen most months but are strongest in the rainy season, roughly July to December. They often begin near the last quarter moon. Local guides track activity and can advise on timing.
Arribada Planner
| Factor | Detail |
|---|---|
| Peak season | Roughly July–December |
| Moon timing | Often near last quarter moon |
| Guide | Certified local guide required |
| Lights | Red light only; no flash |
| Access | 4x4, possible river crossings |
| Distance from Nosara | ~15–20 min |
| Fee | Refuge and guide fees apply |
| Clothing | Dark, closed shoes |
Times, seasons and conditions are approximate; confirm locally before travel.
Visitor Rules
Entry to the nesting beach requires a certified guide from the local association. Do not use flash photography or white lights, stay behind turtles and never touch them or hatchlings.
Getting There
Ostional is a short drive north of Nosara on a dirt road that may require river crossings in the rainy season. A 4x4 is recommended.
Olive Ridley Biology in Brief
Olive ridleys are among the smallest sea turtles, with adults weighing roughly 35 to 45 kilograms. Females can nest several times in a season, digging a flask-shaped chamber and laying around 100 eggs that incubate for about 45 to 55 days in warm sand. Sand temperature influences hatchling sex, with warmer nests producing more females. Ostional is also notable for a legally regulated community egg harvest during the first hours of an arribada, when eggs would otherwise be destroyed by later-arriving turtles; this program is managed by the local development association under scientific supervision.
A Responsible Night at Ostional
Plan to meet your guide at the local association office, pay the refuge fee and receive a short briefing. Wear dark clothing and closed shoes, bring a red-filtered headlamp and leave the camera flash off. Walk single file behind the guide, never stand in front of a nesting turtle and give hatchlings a clear path to the sea. Avoid sunscreen and insect repellent on hands if you might handle sand near nests.
Where to Stay and Combine
Most visitors base themselves in Nosara near Playa Guiones and make the short trip north. Combine an arribada with surf lessons, yoga classes and sunset at Playa Pelada. Daytime visits to the Ostional beach can also reveal nests and hatchlings during an arribada.
Best Months to Visit
Arribadas occur year-round, but the largest are usually from July to December, often peaking around September and October.
Getting to Ostional
Ostional is about 20 to 30 minutes north of Nosara on rough dirt roads that may require a 4x4 and can flood in the rainy season. Guided tours handle transport and timing.
Photography Rules
Flash and bright lights are banned at night; follow your guide's directions.
Recommended Tours
Nosara Río Montaña & Mangrove Kayak or Stand-Up Paddle Tour
Paddle quiet mangrove tunnels near Nosara and Ostional with a local naturalist guide spotting howler monkeys, herons, and crocodiles.
Check before booking: Tide-dependent start time, kayak vs SUP choice & sun protection.
Nosara Playa Guiones Surf Lesson with Local Instructor
Learn to surf or refine your turns on Playa Guiones' remarkably consistent sand-bottom waves just south of Ostional.
Check before booking: Board and rashguard inclusion & morning session time.
Nosara River Wildlife Safari Float with Transfers & Fruit Snack
Gentle, family-friendly safari raft down the Nosara River habitat for monkeys, iguanas, and tropical kingfishers.
Check before booking: Hotel pickup in Nosara/Guiones & camera dry bag.
Living at Coco Beach: Why Playas del Coco Works as a Guanacaste Base
Turtle season on the Nicoya Peninsula often draws travelers who later explore the rest of Guanacaste. Playas del Coco, about two-and-a-half hours north of Nosara and roughly 30 minutes from Liberia International Airport, offers a calmer, service-rich base for people who want to stay longer.
Unlike resort-only enclaves, Coco is a working beach town. Supermarkets, pharmacies, banks, clinics, hardware stores and dozens of restaurants sit within a few minutes of the bay, and neighboring Playa Ocotal, Playa Hermosa and Playa Panamá offer quieter coves for swimming and snorkeling. Dive boats leave daily for the Catalina Islands, sportfishing and sunset catamarans depart from the same beach, and Rincón de la Vieja's hot springs are an easy day trip.
For people ready to put down roots, Serena Condos sits in the residential corridor between Playas del Coco and Playa Ocotal, about five minutes from the beach and Main Street. Its low-density buildings offer three-bedroom, two-bathroom residences with prices from the $320's, resort-style pools, a fitness center, coworking space and 24/7 gated security, plus optional property management for owners who split their year between Guanacaste and home. Foreign buyers hold the same fee-simple title rights as Costa Rican citizens.
Frequently Asked Questions
When can I see the arribada at Ostional?
Most often from roughly July to December, near the last quarter moon.
Do I need a guide at Ostional?
Yes, visitors must be accompanied by a certified local guide.
Can I take photos of nesting turtles?
Only without flash or white light, following guide instructions.
Partner disclosure: We may earn a commission when you book through our partner links at no extra cost to you.