• Jill Reed, Ph.D.

Olive Ridley Sea Turtle Arribada in Ostional, Costa Rica with Kids

Updated: Oct 23, 2020

About Arribada

Living in Costa Rica affords one many opportunities for appreciating the natural world. This is the land of many different creatures including sea turtles. Toward the end of the rainy season in October and November something special happens here called Arribada.


Arribada is the arrival of the turtles to lay their eggs and the time during which hatchlings make their way from the nest to the ocean. Usually timed with the arrival of the full moon, this amazing feat of nature is something to behold. 


Only two species of sea turtles engage in Arribada nesting when many females come ashore at one time to all lay eggs together. It is thought that the Olive Ridley and the Kemp’s Ridley turtles use this practice to ward off predators with safety in numbers.


So, last week, we woke up and left our house at 3:00am to drive to Ostional for this special occasion. Ostional is home to Arribada for Olive Ridley turtles and has a reputation for being a spectacular event.

About the Olive Ridley Turtle


The Olive Ridley turtle is so named because of the olive color of its heart shaped shell. One of the smallest sea turtle types, they can grow up to two feet in length and can weigh over 100 pounds. These beautiful creatures only nest in a few places in the world and are prevalent in tropical Atlantic, Pacific and Indian Ocean waters.


The Pacific coast of Costa Rica supports an estimated 600,000 nesting Olive Ridleys between its two major arribada beaches, Nancite and Ostional. Nowhere else on earth has this many nesting females. One location in Mexico, La Escobilla, Mexico, claims an estimated 450,000 nesting female turtles. 


In the Atlantic Ocean Brazil has reported growth in numbers, but along the coast of Africa and in the Indian Ocean, the Olive Ridley nesting numbers are declining.

Ostional, Costa Rica


Over a period of several days hundreds of thousands of Olive Ridley turtles crawl from the waves and make their way onto the beach. It took an hour and half to drive from Conchal to the nesting ground. 


We met our guide around 4:45am, parked and met our guide for the first portion of the tour to see the laying moms. As soon as we stepped onto the beach, we almost stepped on three mamas. You have to be very careful. 


For the second part of the tour we walked through a rushing rainy season river to get to the hatchlings. Due to Covid regulations and turtle protections, space is limited so we followed friendly suggestions and made a reservation with a guide. Supporting the local economy is very important right now.


Our guide, Gilbert Rojas Araya, was fantastic, full of knowledge and great with the boys. There are guards on the beach to protect the turtles and the eggs. They are also monitoring people.

The Experience

When we arrived there were turtles, eggs and hatchlings everywhere! It was magical. My youngest son saw a struggling baby right away who was wandering in circles with a stunted flipper. He immediately wanted to assist the baby in getting to the ocean, but our guide reminded him that assistance is not allowed.


Some will make it and some will not. 


As for the nesting females, those with more experience find the process more navigable, while other younger turtles fumble a bit and have more trouble digging their nests and successfully concealing their eggs.


Sometimes the nesting females are so close together the nests get more dug up than they are properly concealed. I can imagine they are exhausted by the time they start laying eggs. They have hauled themselves on their flippers out of the water and past the high tide line to dig a massive hole for a nest. 


Predators also exist. Birds, dogs, and other creatures lurked about looking for breakfast. Local residents are allowed to remove 10% of the eggs for human consumption. This is a tradition as they believe the eggs are good for various ailments.


Don’t be sad. Olive Ridley turtles can lay somewhere in the vicinity of 100 eggs, each one the size of a ping pong ball. That’s a lot of eggs and we saw many of the hatchlings get all the way to the water.


This is a wonderful rainy season experience with kids. May you have the chance to see this wonder, too.

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