Calls only: +506 4070-2220 or +1 954-827-9345 | WhatsApp only: +506-8868-6481

Osa aventura

Your specialists in research support & education


Why the Osa?

It is the country’s best kept secret! It is certainly the most remote and least spoilt area of the country, and over one third of its pristine beauty is protected by Corcovado, the crown jewels of Costa Rica’s National Parks. And these forests are the most majestic in Central America, rivaling in grandeur the best that the Amazon can offer.

Stronghold of endangered species

It is the last stronghold in Costa Rica — indeed, in some cases, Central America! — for many endangered species. To name but a few:
*The Jaguar — these large, secretive cats are not often seen, but their foot prints are everywhere!
*Baird’s Tapir — a common sight in Corcovado!
*The White-Lipped Peccary — large herds of this aggressive species are regularly encountered in Corcovado!
*The Central American Squirrel Monkey — the Osa is the center of this species’ very limited distribution!
*The Scarlet Macaw — the Osa holds the highest population density of this rare bird anywhere in its range. It is not uncommon to see these colorful parrots in flocks of up to one hundred individuals!

National Geographic reference

The forests of the Osa are home to the richest assemblage of plants and animals anywhere in Central America. Over 700 species of trees, for example, have been recorded in the area, many times more species than found in the whole of the North American continent. The National Geographic described these forests as ‘the most biologically intense on earth’. Indeed, the stupefying abundance of wildlife in Corcovado will attest to this; there are monkeys everywhere; sharks and crocodiles feeding together in the Park’s river mouths; and jaguars patrolling the beaches for nesting turtles. And the birds? Wow!! Just being in these forests is like experiencing a living wildlife documentary!

4 + 13 =

Your journey

Osa Aventura offers all inclusive high quality programs  expertly designed to fulfill the adventurous spirit in you. Reef and rainforest explorations are edifying and exhilarating – and often hands-on!

Our prices include all meals, transportation, park entry, accomodation and a bilingual expert, so that you can rest assured that everything has been taken care of.

Kindly read the detailed description and related information to optimize your time, as sometimes we are unable to answer email queries when we are out in the rainforest with limited internet connection. 

our values

The foundations of Osa Aventura’s operations are the ethics of professionalism, reliability and integrity. It aims to introduce people to fascinating natural richness and beauty of tropical rainforests, and thus to make a contribution, however small, to the collective awareness of the urgent need to conserve these precious environments.

The establishment of Osa Aventura was for me an indulgence. I am an adventurer by nature and all of my life I have had an insatiable passion for tropical rainforests. And it is, after all, human nature to want to excite our interests and passions in others. So Osa Aventura has formulated adventure and exploratory tours with this intention.

Osa Aventura is based in the provincial town of Puerto Jimenez, on the Osa Peninsula. It presents on this site a selection of adventures tours designed to explore the length and breadth of the remote Osa Peninsula (see “Why the Osa?”). Based on many years living and working in the tropics, and on an extensive knowledge of the Osa, I have tailored a selection of multi-activity, adventure itineraries to explore the most spectacular and exciting aspects of this pristine, wild Peninsula.

Trail etiquette

1. The instructor must take the lead at all times. Please keep an at least 2-meter distance from people hiking in front and behind you.

2. Hike in a single file to minimze the risk of snake-bite injuries.

3. Hike at the comfortable pace of the slowest hiker.

4. Agree / ask for bathroom or snack breaks when required.

5. Do not go off the trail, approach, startle and / or feed animals.

6. Take your garbage with you; do not leave it at the station.

7. Do not enter the station with food (sandwiches or cans, etc.).

8. Keep noise to the mínimum; do not disturb the fellow visitors. Pack your backpack before nightfall.

our teaM

Mike Boston

Business Owner, Biologist

Jorge largaespada

Safety advisor

marcelLo carvajal


ready for adventure?


What are the regulations in Corcovado National Park?

Changes to Corcovado National Park Regulations
The following are changes to the regulations governing Corcovado. Guide Associations on the Osa Peninsula are trying to reverse these change, but for the time being they hold:
1. The trail from Los Patos to Sirena can only be hiked with a guide.
2. The trail from Sirena to San Pedrillo is closed for this coming dry season (normally it opens from December to April).
3. It is currently not possible to rent the canoes on the Rio Sirena.
4. For the time being, it is not possible to leave any rangers station after dark and, thus, it is not possible at the moment to do night tours.

When is the best time to visit Osa?

All year round. However, March is the hottest and November is the wettest,

Are the hikes difficult?

The hikes are about 20 km long. Both hiking trails, Sirena –Los Patos and Sirena – La Leona, are longer than most people have walked in their lives. They are not difficult technically, but they are demanding on your stamina. The weather is almost always hot and humid, and therefore you should ensure that you are well hydrated and have a good level of electrolytes before the hike. During the hike you will pass by several rivers where you have the chance to cool off.

What is the weather like?

Remember that you are in the tropics: it is hot and humid, and there are snakes and creepy-crawlies. It is the latter though, which concerns people the most. Well, snakes and insects are not as bothersome as your imagination would have you believe. It is the combination of heat and high humidity that is the greater problem. On the Osa Peninsula temperatures seldom drop below 27oC (80oF), in the rainy season, and may exceed 35oC (95oF), in the dry season. Combined with the high humidity (60 – 100%), conditions here can become uncomfortable, even oppressive. Physical activity in such conditions is much more tiring than in cooler climes, and unless you take the appropriate precautions, severe sunburn, heat exhaustion, sunstroke and dehydration are likely consequences. Your guide will give you precautionary advice during adventure tours.

We recommend you bring with you:

  • Light clothing
  • An effective sun block
  • Sunglasses and a peaked cap or a wide-brimmed hat
  • Water bottle of one liter (2 – 3 pints) or more

On the OSA Peninsula rainfall is from 4 to 7 meters (160 to 280 inches) annually, and falls mainly between the months of April and November, heaviest in October. During this period–referred to by Costa Ricans as winter–it rains every day, though usually as heavy showers in the afternoon and evening. At times, rainfall can be torrential and accompanied by thunder and lightning. These thunderstorms, if they persist, can interrupt schedules as a result of swollen rivers and flooding. During such times Corcovado Park can be inaccessible and roads impassable. Throughout the rainy season forest trails will be muddy and in places slippery.

We recommend you bring with you:

  • Light washable hiking boots or rubber boots, both with good grips
  • sealable plastic bags and/or bin bags to keep your belongings dry
  • Light waterproof clothing
What about bugs?

Spiders, like snakes, have an exalted position among people’s phobias. There are a lot of spiders here, but most are small and innocuous. Tarantulas are cryptic and seldom seen; they are harmless anyway!

Scorpions are not that often encountered, and none of the species found in Costa Rica are known to be dangerous. In fact, their stings are scarcely more harmful or painful than bee stings. However, shake out your boots before putting them on!

Biting insects
`Biting’ insects come in several groups, but only three are worthy of mention: mosquitoes, midges (or no-see-ms) and horse flies. Actually these flies (Diptera) don’t bite; they pierce and suck! – No matter where you are, or at what time of the day and night, they have you covered. But, their nuisance value is not that high (at least not anything like as bad as we have experienced in parts of North America and Europe), and most repellents confer effective protection.

Stinging insects
`Stinging’ insects, the bees, wasps, and ants (Hymenoptera) are very prevalent, and while their stings can be very painful, unprovoked attacks are rare. So called `killer bees’ do occur in Costa Rica, but the threat from them is no greater here than in any other area of their range.

We recommend you bring with you:

  • Insect repellent
  • Antihistamine tablets
  • Cream for alleviating insect bites and stings
Are there potentially dangerous animals?

The word `jungle’ conjures up nightmare images in the minds of many people of a place seething with snakes. Well, the reality is quite different (alas!): you seldom see snakes! Most encounters with snakes are with non-venomous species. Nevertheless, the threat from venomous snakes does exist, and their bites can be very serious indeed, sometimes fatal. However, your chances of being bitten by one are about as improbable as being struck on the head by a falling coconut. Venomous snakes will rarely bite unless provoked, trodden on or grabbed. Your experienced guide is there to minimize that improbability and will take the lead on all treks.

Of the large mammals found in the Neotropics – of which there are surprisingly few – it is only the peccary that has a dubious reputation. They have been known on occasions when taken by surprise, to send the unwary hiker scurrying up a tree for safety. Encounters with peccaries (the larger white-lip peccary in particular), in herds of 20 or more, are common in Corcovado and, as yet, no casualties have been reported. Their foul smell and the loud cracking of their canine teeth when alarmed, make encounters with these beasts an awesome experience, and a memorable one! We recommend that you practice your tree climbing!!

Jaguars are large and powerful cats, but have never, contrary to expectation, been known to bother people. There is a relatively healthy population of these cats in Corcovado!

Pumas, reportedly, have on a couple of occasions `tumbled’ people in Corcovado Park. No serious injuries resulted. Personally, we would rather see and be `tumbled’ by a puma than not see one at all!

Sharks are prevalent in the coastal waters of the Osa Peninsula and the Golfo Dulce. And among their ranks are two of the three most infamous species: the tiger shark and the bull shark. While this area is not renown for shark attacks, they have been known to occur – though no fatalities as far as we are aware. Bull sharks are very often seen patrolling the mouths of the Rio Sirena and Rio Claro in Corcovado Park. The benign white-tipped reef shark is a common sight to divers off Caño Island.

American crocodiles
American crocodiles kill on average one person annually in Costa Rica. In recent years these have been tourists! This species does not have a particularly bad reputation, preferring fish to tourists. But large specimens of three and a half meters (12 feet) or more will take large mammals and even people. Because of Costa Rica’s rigorous conservation laws, specimens of this size and larger are common here – reportedly there are crocodiles of up to 6 meters (20 feet) in the Corcovado Lagoon. But the American crocodile is not a threat unless you are dumb enough (or crazy enough like me!!) to swim in rivers, lagoons and lakes where they are known to occur. 

What precautions should I take?

A Precautionary Note
Hopefully we have allayed some of your fears and phobias about the tropics; or at least put them in perspective. But please don’t become too complacent: there are hazards and dangers in tropical rain forests and coral reefs.

Getting Lost
Getting lost in rainforests, for example, is a very real possibility if you are foolhardy enough to stray from the trail and your guide. When surrounded by trees with visibility restricted to 30 meters (100 feet) or less, one has no point of reference by which to navigate. And while the adage that all rivers lead to the sea is true, in Corcovado many rivers have their seaward courses interrupted by crocodile-infested swamps! Slippery trails and protruding roots make real the possibility of tripping and breaking a bone. Some trees, especially some palm trees, have vicious spines which, can cause deep wounds, can be difficult to remove, and often cause suppurating wounds.

Some Perspective
Although perils can come from unexpected sources, tropical rain forests and coral reefs are not seething cauldrons of nightmares as some may fear. If entered with due respect and perceived for what they really are–incredibly diverse and complex interrelationships of living things–tropical rainforests and coral reefs are truly among the most fascinating and captivating ecosystems on Earth.

Medical Advice and Vaccinations
Costa Rica has had for several decades an excellent health service. As a consequence, many of the diseases prevalent in other tropical countries have long since ceased to be a problem here. Nevertheless, you should seek medical advice from your doctor or medical center about what vaccinations are required and recommended for Costa Rica.

Dengue Fever and Malaria
Dengue fever and malaria are both on the increase world wide, and have recently reappeared in this country. Dengue and malaria are transmitted from people to people by mosquitoes, with no other animal host involved. Risk from either disease is, therefore, greater in urban areas than in rural areas. The Osa Peninsula has seen only a handful of cases of these diseases in the last two years largely because it is mainly rural. Concern for dengue and malaria in Costa Rica is centered primarily in the urban areas of Puntarenas, along the Pacific lowlands, and in Limon, along the Caribbean lowlands.

Waterborne Diseases
Waterborne diseases, such as cholera and typhoid are virtually unknown in Costa Rica, and municipal water supplies throughout the country are for the most part chlorinated and potable. The incidence of hepatitis is 100 times greater than typhus and 1000 times greater than cholera. The protozoan Giardia and the bacterium shigella are widespread in natural waterways. Under no circumstances should you drink water from a stream. Avoid shistosomiasis by not swimming in very slow-moving water.

Minor Infections
Minor infections, common to all humid tropical areas, include fungal rashes, like athlete’s foot and jock itch. Wearing damp clothing on long hikes through Corcovado offers ideal conditions for these rashes to occur. Also, cuts and grazes can become more easily infected with bacteria in tropical conditions.

We recommend you bring with you:

  • Anti-fungal cream
  • Antiseptic lotion or swabs
  • These in addition to other items recommended by your medical center or Doctor
What should I bring and wear?

Please note that on these adventure tours through Corcovado Park we will be hiking, with backpacks, for 50kms (30 miles) or more along muddy trails and beaches. As we have explained, the greatest difficulty you are likely to experience is from the combined effects of heat and humidity, which, if you are not used to it, can be debilitating. For your own comfort, therefore, we strongly advise that you to travel as lightly as possible: bring only that which is essential to you. You will be advised on these matters during your pre-tour briefing, and arrangements to store excess baggage can be made.

The following is what we recommend you include when packing:

  • Binoculars
  • Camera & film (asa 400 to 600 is best in rainforests)
  • Compass
  • Multipurpose penknife
  • Flashlight & spare batteries
  • Small zip-lock bag for your passport etc.
  • Bin-bags for clothing etc. (purchasable upon arrival)
  • Water bottle
    This list includes some items essential and recommended for inclusion in your personal medical kit. Tailor your medical kit to your own specific needs, and perhaps seek medical advice. But keep it light! Remember that your guide will be carrying a multipurpose medical kit on all tours.
  • Blister band-aides
  • Antihistamine tablets (good for suppressing irritation from insect bites)
  • Cream to alleviate insect bites and stings
  • Antiseptic lotion or swabs
  • Anti-fungal cream
  • Sun-block
  • After-sun lotion
  • Insect repellent

  • A light sheet (a sleeping bag liner is ideal)
  • Peaked cap or wide-brimmed hat
  • Sunglasses
  • Sandals
  • Comfortable hiking boots or shoes with good grips (light ones that can be easily washed and dried are best). We wear rubber boots!
  • A 65 to 75 liter backpack of good quality. (Multipurpose backpacks which double as suitcases are not recommended). A large pack half filled is much more comfortable than a small pack stuffed full!
  • One pair of light trousers and a light long-sleeved shirt
  • 3 pairs of shorts and 4 T-shirts. (To save weight consider hiking in the same clothes each day, packing only the minimum of clothing you think you will need for a clean, dry change in the evenings)
  • Several pairs of good quality hiking socks
  • A light backpackers towel
  • As much underwear as you require
  • Swim-wear

What Osa Aventura Provides
We are equipped with a medical kit, flashlights, and binoculars, but we recommend that you bring your own. Osa Aventura is also equipped with the knowledge of the environment, the terrain and its potential dangers. It is important that you heed the advice given to you by your guide during these adventure tours.

Your recommendations for scuba diving?

PADI Resort Course instruction, prior to diving, is given to those of you who wish to scuba dive but lack diver’s certification. However, it has been our experience that many novices have pulled out of diving during the PADI instruction because of problems they have had using a facemask and snorkel, and/or a breathing regulator. It is a reflex action to stop breathing when one’s face is immersed in water, and to do so through a snorkel or regulator takes some getting used to. If you are unfamiliar with a facemask and snorkel, buy both and practice using them in the bath or your local swimming pool before your trip. And if your local diving club is willing, seek some practice with a breathing regulator as well.

Another problem, which we have come across, is with people who are near-sighted. It is not possible to wear glasses under a facemask; only contact lenses. So if you are near-sighted please don’t forget to bring contact lenses, and spares. Also, make inquiries about prescription facemasks.

Unless fear of water, feelings of claustrophobia, or other strong considerations prohibit you from scuba diving, we urge you strongly to give it a determined try. We of Osa Aventura have designed these adventure tours to introduce you to the beautiful, the awesome, and the amazing inhabitants of the world’s two most biologically rich environments — tropical rain forests and coral reefs. Not only would it be a great regret to you to miss experiencing one of them, but it would be huge disappointment to me as well.

Experienced Divers
If you have scuba dived before, beyond the level of resort diving, please bring whatever certification you have that will verify your experience. You may also use these dives on Caño Island to further your diving qualifications. We would need some prior notification if this is your wish, and you will incur an additional cost for the instruction.

All diving equipment is provided. However, if you are planning to bring your own personalized facemask, fins or wet suit consider the additional weight which you will have to carry on the adventure tour that involves hiking through Corcovado National Park for several days.

Advisory Note
While diving you must keep within sight of your dive leader: stay close if you are a novice. And you must follow to the letter the instructions, warnings and advice he or she will give to you on each dive. None of the sea creatures you will encounter will be a threat to you if left alone.