Playa Ostional: where olive ridleys arrive in the tens of thousands

What is an arribada?#

A synchronised mass nesting. Instead of arriving individually, olive ridley females come ashore together over three to seven consecutive nights, in numbers that reach the tens of thousands at Ostional. They most often begin on a rising tide in the last quarter of the moon. It happens in most months and is largest between July and December.

Ostional is one of very few beaches in the world where this occurs, and the only one in Costa Rica where a strictly regulated harvest of eggs from the first nights is permitted — the reasoning being that later females dig up those clutches anyway. The refuge is administered by SINAC, and the local association manages access.

How do you visit?#

With a licensed guide, arranged in the village. The beach is closed to unaccompanied visitors during an arribada, and going out alone at night is neither allowed nor sensible. Guides work to the tide and the moon rather than to a timetable, so an arribada cannot be booked far in advance — the practical approach is to be in Nosara during the season and ask daily.

Why is the water off limits?#

Every reason at once. Strong permanent rips run the length of an eight-kilometre open beach, the shore break is heavy, there is no lifeguard, and the concentration of nesting turtles and eggs draws sharks close in. The people who live in Ostional do not swim there either, which is the clearest answer available.

What is the road like?#

Unpaved from Nosara with two river crossings, the first of which — the Rio Nosara — is impassable at high tide and after rain. Check the tide before setting out, and be clear about when you plan to come back.