Size: 162 hectares of land and 587 hectares of sea
Distance from San José: 371 kilometers via Liberia
Dry season: January through March
Turtles nesting: July to November during wet season

Nancite Beach in Santa Rosa National Park and the wide beach at Ostional constitute the world's two most important nesting sites for the olive ridley turtle. The sector of the beach where the turtles arrive measures about 900 meters long and is located between a rocky point and the estuary of the Ostional River, which in part runs parallel to the beach.

This refuge contains the second most important nesting site for the Olive ridley turtle in Costa Rica, the first being Nancite Beach in Santa Rosa. The turtles sometimes come ashore in huge numbers, during the months of July to November. This is the wettest time of the year in Nicoya, when the roads are often in horrific shape, but if you want view sea turtles on the Pacific side, this is the time and place.

The olive ridley turtle arrive every year at Ostional Beach in huge arribadas that last 3-7 days and that usually takes place at night during the months of July through November. Although four or five arribadas can take place in a year, there have been years when as many as 11 have been recorded. Other species of sea turtles occasionally nest here are the leatherback, the largest of all, and the Pacific green. When the arribada season is over, the beach is completely pockmarked with hollows of almost half a meter in diameter that were the nests made by the turtles and that take on this appearance when the baby turtles hatch and make their way down to the water. Dry, white eggshells and broken eggs can also be seen everywhere.

In Ostional is working a program in which people from the village of Ostional, have the right to collect 200 eggs per family per season. These are sold for about 3 colones each to a middleman, who then distributes them locally and in San José. Although this gives local people a stake in protecting the turtle population from the illegal, uncontrolled collection of eggs by poachers from outside the community, it's argued that this just encourages turtle poaching elsewhere in the country by opening a loophole for illegal street vendors, who simply say that all of heir eggs come from Ostional.

During the nesting season, there is almost always someone from the egg cooperative at a guardhouse near Punta India, and they are usually glad to take you out to see the turtles at night or to discuss with you their thoughts about the egg business and turtle conservation.

All over Ostional Beach are two large populations of amphibious, predatory crabs which are typical on sandy beaches: beach ghost crabs. During the dry season the Ostional River dries up, but as there is always water in its estuary, it turns into an excellent habitat for different species of fish, birds, crabs and other animals.
Southeast of the refuge, at the mouth of the Nosara River, there is a large mangrove swamp where 102 species of bird have been identified.

The rocky area that lies in the northwestern corner of the refuge near India Point offers a great scenic beauty and innumerable tide pools where it is easy to observe seaweed, sea urchins, starfish, sea anemones and many very colorful little fish. Crabs, especially those known as Sally lightfoot, ghost, and hermit, abound in the area.

Birds found here: brown pelican, frigate bird, American oystercatcher, royal tern, Neotropic cormorant, cattle egret, roseate spoonbill, wood stork, spot-bellied bobwhite, black-bellied plover and white-fronted amazon.

Animals found here: Howler monkeys, white-faced capuchin monkeys, tree squirrels, white-nosed coatis, kinkajous, ctenosaurs and basilisks.