This little-visited national park is where five of Costa Rica's major rivers originate. The 143-sq-km reserve has a sizable but little maintained trail network and few facilities. In fact, you'll likely have the park to yourself. Most folks head to the visitor center (4WD required) managed by Montaña Sagrada Natural Reserve, and walk the three trails there. One goes to a dreamy lagoon named Ponzo Verde. The infrequent foot traffic means that your chances of spotting unusual species is greatly increased.
Keep your eyes peeled for tapirs, ocelots, curassows, quetzals and black guans. There are also many orchids.