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Whether you stay at the Piro Research Center or the Greg Gund Conservation Center, there is plenty of room to explore your surroundings.
This map will get you oriented to the campuses, where they are on the Osa Peninsula, and how they relate to each other. 
Click here for a printable version of the Osa Biodiversity Center Trail Map.
Click here for a printable version of our Trail Information.
You can explore our trails in a number of formats from our Resources section.
Trail Information
The network of trails running through the Osa Biodiversity Center and surrounding primary rainforest offers naturalists, scientists, and recreationalists access to a vast array of tropical plant and animal species. Made up of varying lengths and difficulties, the trails explore several microhabitats providing days of enjoyment and learning. Whether it is the Piro trail along the river habitat containing Bare-throated Tiger Herons or the Ocelote trail under enormous Ajo and Fig trees where spider monkeys take residence, each path is easy to navigate thanks to meticulous mapping and trail marking systems. Below you will find elevation charts and descriptions about each trail.
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Ajo Trail
Distance: 1.1 Km
Difficulty: Moderate
Duration: 40 Mins |
From Piro Research Center towards Greg Gund Conservation Center |
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The beginning of this trail is less than 100 meters from the Cerro Osa trailhead. Like the Cerro Osa Trail, the Ajo boasts some of the most beautiful rainforest that the Osa Peninsula has to offer. Although not found only on this trail, the ajo (Caryocar costarricense) trees that you'll see are the largest we know - reaching over 40 m tall, they do not go unnoticed. The common name ajo means garlic in English and comes from the fact that the fresh flowers and bark of the tree bear a distinctive garlic scent. Its gigantic size and very hard wood resistant to adverse tropical climatic conditions made this one of the most sought-after timber species. Because of their overexploitation, there are few places where you can see ajos of the size observed at the Piro Research Center.
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Cerro Osa Trail
Distance: 2.7 Km
Difficulty: Difficult
Duration: 1 Hour |
From Piro Research Center towards Greg Gund Conservation Center |
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This trail is an old logging access road that now connects the Piro Research Center to the Greg Gund Conservation Center. The first 1.4 km of this trail, starting from the Piro Research Center, transitions from 20 year old secondary forest to mature forest, making it a great place to explain the differences between these two forest types. With an altitudinal gradient of approximately 150 m, you will see wonderful old-growth forest conditions with trees reaching over 30 m high and where spider monkeys (Ateles geoffroyi) are commonly observed. At 1.4 km you'll reach a gate that marks the beginning of the Cerro Osa property, another part of the Osa Biodiversity Center. The next 0.7 km of the trail takes you through abandoned pochote (Bombacopsis quinatum) plantation and back into lush forest as you come through a branch of the Coyunda watershed on the way up to the Greg Gund Conservation Center.
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Chicle Trail
Distance: 4.4 Km
Difficulty: Difficult
Duration: 3 Hours |
From Greg Gund Conservation Center to Access Road |
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Starting from the native tree nursery at the Greg Gund Conservation Center, you will descend along a forested ridge that gives you a dramatic perspective hard to find on other trails as both sides drop away into the calming sound of the Coyunda stream below. After crossing the Coyunda, you'll wind your way up through the forest and along yet another ridge with a view to the Pacific. The second half of this loop follows the road and passes through a 50 acre forest restoration plot where we are using bat roosts and bird boxes to naturally restore abandoned pochote plantation to ecologically vibrant rainforest.
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Chiricano Alegre Trail
Distance: 1.2 Km
Difficulty: Difficult
Duration: 45 Mins |
From Piro Research Center to Cerro Osa Trail |
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This trail starts near the dining hall and connects the Piro Research Center clearing to the Cerro Osa Trail. Shortly into your walk you will use a fallen-tree bridge to cross the Coyunda. The two small water crossings on this trail make it one of the better places to glimpse a river otter (Lutra longicaudis) or even a greater grison (Galictis vittata), both of which have been observed here despite their very rare status. With an altitudinal gradient of approximately 100 m, this trail will take you through 10 year old secondary forest, an old vanilla plantation and finally mature forest, where you will find a huge Chiricano Alegre (Vantanea barbourii) tree.
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Los Higuerones Trail
Distance: 0.3 Km
Difficulty: Easy
Duration: 15 Mins |
From Piro Access Road to Cerro Osa Trail |
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This short trail (0.33 km) connects the Piro Research Center access road to the Cerro Osa Trail. Los Higuerones traverses 20 year old secondary forest, where the dominant trees are figs (Ficus insipida), for which the trail is named. These trees, belonging to the family Moraceae, are of great ecological importance as they provide food and shelter for countless species. Although commonly referred to as a fruit, the fig is actually the flower of the tree, known as an inflorescence (an arrangement of multiple flowers) in which the flowers and seeds grow together to form a single mass. The flower is not visible, as it blooms inside the fruit. The small orifice visible on the middle of the fruit is a narrow passage called the ostiole, which allows a specialized wasp to enter and pollinate the flower, whereafter the fruit grows seeds. These 1-2 mm long wasps from the family Agaonidae have coevolved with fig trees, with each species of Ficus maintaining a symbiotic relationship with a particular species of wasp.
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Los Perdidos Trail
Distance: 1.5 Km
Difficulty: Difficult
Duration: 1 Hour |
From Chiricano Alegre to Ocelote |
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Los Perdidos connects the Chiricano Alegre and Ocelote Trails. Located in mature forest with a number of natural clearings created by fallen trees along the way, the trail provides the perfect opportunity to observe how natural regeneration works and introduce visitors to the theory of light gaps, which explains why tropical forests are so diverse. This trail winds through a network of older footpaths formerly used by our neighbor Miguel Sánchez; so visitors should keep a close eye on the trail markers to avoid getting lost. While not unique to this path, several manakin leks have been observed, of both Red-capped (Pipra mentalis) and Blue-crowned (Pipra coronata) manakins. Leks, common in several species of birds, consist of sites in which males perform displays to attract females. Manakin leks are usually easy to find since the birds make a very distinctive clicking noise with their wings as part of their display.
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Northern Border
Distance: 6.6 Km
Difficulty: Difficult
Duration: 3.5 Hours |
From Greg Gund Conservation Center to Access Road |
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At 6.6 km with a top elevation of 355 meters above sea level, this loop is by far the most challenging in the Osa Biodiversity Center trail system. The beginning of the loop is the same as the Cerro Osa Trail until you reach the T junction. Taking a left at the T will put you on the Cerro Osa Trail leading to the Piro Research Center. Turning right at the T will keep you on the Northern Border Circle for a long uphill walk through old pochote (Bombacopsis quinatum) plantation. Take the short detour at the top of the hill for a commanding view of the Pacific and a spectacular breeze to cool off after the ascent. If you're looking for the easiest way to complete the loop, try it in reverse and start by heading up the entrance road to the Greg Gund Conservation Center. Either way you choose, the most impressive part of the loop lies along the northern border of the Cerro Osa property where you will pass through majestic old growth and pristine rainforest.
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Ocelote Trail
Distance: 1 Km
Difficulty: Difficult
Duration: 45 Mins |
From Cerro Osa Trail to Los Perdidos |
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Located entirely in mature forest, Ocelote connects the Los Perdidos Trail and the Cerro Osa Trail. This is one of the most stunning walks in the Osa Biodiversity Center trail system, as it combines a number of enormous rainforest trees with a sparse understory, a characteristic of primary forests. The trail was named after two ocelots, one male and one female, were photographed using the hollow of an old baco (Brosimum utile) trunk as a latrine. Interestingly, the researchers also found photos of coatis, opossums, skunks, and tayras, all common ocelot prey, visiting the same spot. Why these animals visit their predator's hangout is still a mystery.
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Piro Trail
Distance: 1.6 Km
Difficulty: Easy
Duration: 45 Mins |
From Piro Access Road to the beach |
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This trail winds along the western bank of the Piro River through 15-20 year old secondary forest. It is common to see birds like the White Ibis (Eudocimus albus), the Boat-billed Heron (Cochlearius cochlearius) and five different species of Kingfishers, all of which use the rivers to look for food. While not very common, it is possible to observe river otters (Lutra longicaudis), an aquatic mammal considered at risk of extinction, along the Piro Trail. This 1.6 km trail meets the Terciopelo Trail near the beach.
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Las Rocas Trail
Distance: 0.4 Km
Difficulty: Easy
Duration: 15 Mins |
From Terciopelo to the beach |
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Branching off from the Terciopelo Trail as an alternate route to Piro beach, Sendero Las Rocas shares many of the same characteristics. The trail is 0.45 km and ends in an often flooded area dominated by spiny palms (Bactris major) between the forest and the beach. Depending on the tide and the course of the Piro River, the water level can reach 40-100 cm. The trail ends near a rocky outcropping where temporary tidal ponds form, allowing you to see interesting marine invertebrates. Locals often fish on these rocks, but you should be very careful when the tide is rising, as powerful crashing waves make this a potentially dangerous pastime.
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Terciopelo Trail
Distance: 0.7 Km
Difficulty: Moderate
Duration: 40 Mins |
From the road to the beach |
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Terciopelo is the name used in Costa Rica to refer to the venomous Fer-de-lance snake (Bothrops asper). This trail bears the name Terciopelo because for some unknown reason it is where our visitors are most likely to see this species of snake. This 0.7 km trail is located in 15-20 year old secondary forest. At the trailhead just off the main road, the forest is dominated by botarrama and wild nutmeg (Virola spp.) trees and as you near the beach it becomes thick with the Vicoyol palm (Bactris major). Depending on the direction the Piro River takes on its way to the Pacific, it is likely that you will need to wade through it to get to the beach. Ask at the station before going to the beach and we may be able to give you a drier alternate route.
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