Ostional

Ostional is one of a handful of beaches in the world where olive ridley turtles nest in a synchronised mass arrival, an arribada, and it is among the largest: over a few nights, usually in the last quarter of the moon, tens and sometimes hundreds of thousands of turtles come ashore to lay, so densely that later arrivals dig up earlier nests. The refuge operates an unusual arrangement, unique in the world: the local community is legally permitted to harvest a controlled share of eggs from the first days of an arribada, on the reasoning that those nests would be destroyed anyway, and that legal supply has been credited with reducing poaching pressure.

What you actually see

• The arribada - tens of thousands of turtles over a few nights.
• The hatchlings - emerging in waves about seven weeks later.
• The legal egg harvest - the community arrangement found nowhere else.
• The black sand beach - long, wild and largely undeveloped.

When to go

Arribadas happen most months but the largest are from July to December, usually beginning in the last quarter of the moon and lasting three to seven nights. They cannot be predicted precisely; the refuge announces them once they start, which means being nearby and flexible.

Honest expectations

You cannot book an arribada: they are announced when they begin and are over within days, so seeing one means being in the area with time to spare. Guides are compulsory and lights are restricted. The road in fords a river that is impassable after rain. The egg harvest is controversial with some conservationists, though it is legal, monitored and long-established.

Nearby

Nosara is twenty minutes south; Sámara is an hour further.