Ph (506) 2735-5036, Ph/fax (506) 2735-5282, fax (506) 2735-5276. The entry costs 6 US$ per person and visit. The park is administered by the Central Office in the Osa Conservation Area, in Puerto Jiménez. There are several forest posts; the main one being Sirena Ph (506) 2770-8222, close to the coast, in the center of the park there is a landing strip. Several footpaths join the other three forest posts that allow you to camp here. If you reserve with plenty of time, the guards will prepare meals for you for 5 US$ breakfast and 8 US$ lunch or dinner. Camping costs 2 US$ per person.
From San Pedrillo to Sirena
From the north, you have to walk along the coast from Drake Bay to the San Pedrillo forest post, about 1 km after you enter the park. The walk takes a day so it might be better to rent a boat. The route from San Pedrillo to Sirena takes 10 hours on foot.
From Leona to Sirena
From the south, you can get here by land or by air to Carate, from where there is a walk to a forest post in La Leona which will take a little more than an hour, from here, the on foot excursion lasts seven hours, you will need to wait for low tide, because you will need to walk along the beach and you will need to cross several rocky areas. You will be able to see mammals, jaguars have been seen splashing about on the beach. The total distance from Carate to Sirena is 16 km.
From Los Patos to Sirena
From the east, you will need to take the bus to La Palma, which arrives at Los Patos forest post after a four hour journey. This footpath crosses the river twenty times in the last 6 km before you get to Los Patos. From Los Patos, a 6 km footpath takes you to a small hill with a viewpoint, where you can see the Corcovado lagoon and part of the park.