The Kori Wayku is the most attractive valley in the area around Coroico — completely forested, wild, and largely untouched. Its river joins the San Juan to form the Yolosa river, and through the valley the Incas built one of their great stone highways. Parts of the trail have been washed away by the river over the centuries, but the surviving stretches are spectacular, in places carved directly into the cliff wall.
The standard outing is a three-hour walk from Yolosa up to a magnificent canyon where the trail clings to the rock face above the water. Leave early so you have time to linger rather than rush. Along the way you can visit a small artisanal gold mine and watch for wildlife in the dense forest. On the return you can either retrace your steps or, when water levels are low, follow the river or cross the valley to climb up to Coroico Viejo, from where the descent back to Yolosa is stunning.
Beyond the canyon the Inca trail is in near-perfect condition, but going deeper into the valley requires at least a two-day expedition with a guide and proper preparation. For a day trip, the canyon makes a fine turnaround point, and the cliff-carved section alone justifies the walk. Bring water, sun protection and footwear you do not mind getting wet.