The San Juan Valley is a broad sweep of cloudforest west of Coroico, mixed with coffee and coca smallholdings and best explored slowly on foot. It is one of the most rewarding day-walking areas in the Yungas, with a network of old footpaths, river crossings and ridgeline trails that link a string of small communities.
The classic approach is to take a minibus to Carmen Pampa, a small village built around a rural university, and from there cross the valley on a beautiful path that spans two suspension bridges high over the river. On the far side a dirt track leads on toward Old Coroico and Yolosa. Old Coroico was reportedly abandoned because locals believed the place was haunted; its historical heart is now an old church tower and a crumbling villa, slowly being reclaimed by the forest. From there one of the area's finest paths descends to Yolosa along a grassy ridge between two forested valleys.
Beyond Carmen Pampa a low pass marks an abrupt change in the landscape, where the cloudforest gives way to open coca fields. One branch of the road follows the bed of an old train line, still walkable as a two-day trek all the way from Unduavi for those who want a longer route.
Most walks in the valley can be done independently in a day, but a local guide adds welcome context about the wildlife, the farming and the history of the abandoned settlements. Bring sun protection for the exposed stretches and good footwear for the river crossings.