For those who love trekking, the 7-hour demanding hike through the cloud forest (las Yungas) is an exercise rich in landscapes and encounters with the flora and fauna of this ecosystem. The trail lies at 1500 to 2200 meters above sea level, offering a great oppertunity to train for altiplano trekks. We begin our day with an hour long hike up the hillside of Las Lauras, identifying along the way the names of Plush-crested Jays and parakeets hidden amongst the thicket, as well as erythrinas and lapacho trees. We continue until we reach La Mina Pass where a tree fern forest nourishes itself with the humidity of clouds that habitually wind their way through the canopy of weinmannias, bolivian pines, bolivian cedars, and myrtaceaes. With a little luck we will cross paths with the Capuchin Monkeys´ aerial route or hear the song of quetzals, trogons, tinamous, guans, thrushes, and antpittas. Once on the other side we will head down for two hours to reach the forest of laurels and bolivian walnut trees. After lunch we will hike for an hour between the wind-twisted trees along the ridge which divides the watersheds of the Piray and Yapacaní rivers. We then reach the parrots´ cliff on the Devil’s Tooth. From a lookout, well inside the park’s borders, the spectacular view of the Devil’s Tooth and the sight of both valleys enshrouded by mist make the trip very worthwhile. Those with strong hearts and ankles can climb up for one hour to the top of the Tooth if they are not daunted by heights. From the lookout we head down for 2 hours towards Piedras Blancas through steep bamboo undergrowth beneath a forest of bolivian walnut trees and laurels. There are many photo oppertunities (200 to 400 ISO). From the Inter-Andean valleys, it takes an hour by 4x4 jeep on a dirt road to reach the trail, and another hour coming back down. Bring raincoat and insect repellent.