Area: 180 acres
Marine Area: Approx. 250 acres
Location: Guanacaste Province
Ostional Wildlife Refuge
There is something extraordinary about Ostional Nacional Wild Life Refuge, just ask the tens of thousands of Pacific ridley sea turtles that lay more than a million eggs on its sand.
Like clockwork, female turtles come ashore during the rainy months of July through November to pass their torch on to the new generation. The massive nesting episodes are known by the locals as arribadas (arrivals).
More than 100,000 nests may be made in one week in the hopes that a large percentage of hatchlings will survive predators such as crabs, coyotes, birds and humans.
After seven weeks in the sand, baby turtles dig their way up to the surface and wait until the cover of night to sprint towards the water. Many years later, as grown ups, these hatchlings will come back to the same shore to lay their eggs and continue the circle of life.
The Ostional refuge gives Mother Nature a hand protecting the beach and the offshore waters around it. Visitors are welcome to witness this phenomenon as long as they don't interfere with the process. The nesting and breaking of the eggs may take a few hours but experiencing the miracle in the making will be well worth your time.
The Ostional National Wildlife Refuge is located in the counties of Santa Cruz and Nicoya in the province of Guanacaste. It is bounded on the North by Punta India 222550 N - 34750 E (Hoja Cerro Brujo 3046-II), the South by Punta Guiones Nosara 210400 N - 353150 E (Hoja Garza 3045-I) and extending three miles out to sea. The refuge comprises an area of 300 Ha on land and 800 Ha of ocean.
Ostional was established as a refuge to protect the olive ridley turtles that nest on this shore. The most important nesting area stretches from a place known as La Roca to the Ostional estuary. In addition to the olive ridley, which nests in the refuge year-round, giant leatherback and green turtles nest from September to February, as well as the occasional hawksbill. Olive ridleys can lay more than 100 eggs each on the refuges beaches. Once a year, a phenomenon called la arribada ("the arrival") occurs between September and November. For three to seven days, hosts of olive ridleys descend upon the refuge to lay thousands of eggs. In order to make reasonable use of this resource, the law permits eggs to be taken from Ostional for commercial purposes. This activity is coordinated with the Ostional Development Association, as are guided turtle-watching tours.
The Ostional National Wildlife Refuge was officially created in 1984 but was declared a protected area in 1982. The refuge was initially construed as being 200m wide from Punta India to the mouth of Rio Nosara. This area was increased to include the 200m strip to Punta Guiones in 1985. Finally, in 1992, with the institution of the new "Wildlife Law", came the final definition of the refuge and in 1993 the amplification to the three mile maritime limit as it is today.
The best time to visit Ostional is just before and during an ARRIBADA. These occur, as a general rule, at the start of the LAST Quarter MOON. The best months to see the biggest ARRIBADAS are between July and December.
After an undetermined waiting time, close to the last quarter of the moon cycle, the "arribada" will begin. At first, a few hundred turtles will come out on the beach, followed by a steady stream of animals for the next three to seven days.
So many turtles come onto the beach in a short time span that most of the first nests are destroyed by later turtles. Therefore, in 1987, a project was initiated to allow local people the right to collect and sell a percentage of the eggs from the first three days of each arribada. This is the only place in the world where it is legal to harvest turtle eggs. This practice is designed prevent poaching and to help the local community.
Ostional Wildlife Refuge
"Arribadas" occur all through the year, at least once a month and, in some months, may occur twice. The months between June and December, during the rainy season, see larger "arribadas". That means that the number of nesting turtles may be in the range of hundreds of thousands as opposed to tens of thousands for the dry season months.
The Ostional National Wildlife Refuge was created to protect one of the world's most important nesting beaches of the marine turtle Lepidochelys olivacea (Olive Ridley) or Lora as it is known locally.
In 1994, the functions of the forestry service, the park service and the wildlife service were combined under the umbrella of the "National System of Conservation Areas" (SINAC) directly responsible to the Ministry of the Environment and Energy (MINAE).
Under this system, the Refuge falls under the control of the "Tempisque Conservation Area" (ACT) which has a wildlife ranger as its representative in Ostional.
The nesting beaches are patrolled by guards who are paid by the village of Ostional.
As marine turtles are normally shy and easily disturbed when nesting, the "arribada" is all the more exciting and strange. These animals, now in "arribada mode", will come out during the night and day and be almost oblivious to disturbance by man or animal, light or sound. Bumping into each other, crawling over each other, they are automatons on their way to fulfill a predetermined task; lay their eggs at all cost.
The largest "arribada" thus far recorded in Ostional, took place in November 1995 when a calculated 500 000 females came ashore.
The Olive Ridley Sea Turtles of Ostional National Wildlife Refuge in Costa Rica are world famous for their arribadas, huge egg laying seasons. The nesting beach at Ostional can be covered with thousands of turtles during an arribada. Although some believe that arribadas may be correlated with moon phases and tides, there are turtles laying eggs at Ostional Beach throughout most of the year.
Park Attractions
The Ostional Wildlife Refuge protects marine turtle species, such as the Olive Ridley (Lora) and Leatherback (Baula) at Playa Ostional on the Nicoya Peninsula Costa Rica. Arribadas at this beach are considered the largest in the world, with as many as a million sea turtle eggs laid in the beach nesting areas each year.
Some days or weeks before an expected "arribada", one may observe an increasing number of turtles swimming close offshore. This is then the gathering of this particular group of turtles that will be taking part in the next event. As an individual will nest between four and six times a year, there will probably be females present that nested in the previous "arribada".
Location and Directions
Ostional Wildlife Refuge can be reached from either Nosara or San Juanillo. See the Road Map above. Tour guides are available in Nosara.
Park Facilities and Hours
The ranger station at Playa Ostional is open from 8 am to 4 pm. Guided tours are available with bi-lingual park employees.
Protected Areas 
