Olive ridley arribada night at Ostional

Once or twice a month in the rainy season, tens of thousands of olive ridley turtles come ashore at Ostional over a few nights to lay their eggs, sometimes packed so tightly in the surf that they bump into each other. It is one of the only places in the world where these mass arrivals, called arribadas, happen at this scale. They are biggest from about August to October, and some ridleys nest on the beach in every month of the year.

The beach is a national wildlife refuge, and you need a trained local guide to go onto it to watch. The village also runs a legal, regulated harvest of turtle eggs through its development association, so do not be surprised to see locals collecting them. Arribadas last a few nights and then stop for weeks, so ask in Nosara or Ostional before driving up.