Most of the popular treks begin near La Paz, traverse the Cordillera Real on ancient Inca routes, and end in the Yungas. The three-day La Cumbre to Coroico Trek, northeast of La Paz , is the premier hike in Bolivia . Other popular treks include the two-day Taquesi Trek, also known as the Inca Trail, which crosses a low pass in the Cordillera Real between Ventilla and Chulumani; the little-known Yunga Cruz Trek, between the village of Chuñavi and Chulumani, which passes over a shoulder of the mighty Illimani; and the six-day El Camino de Oro, or Gold Trail, which heads from Sorata to the Río Tipuani goldfields. The less strenuous walk to the Zongo Valley Ice Caves near La Paz is a spectacular alternative for those suffering cramps or needing to adjust gently to the high altitude. The Cordillera Real also offers great climbing opportunities, including Illimani, 6088m (19,970ft) Huayna Potosí, 5648m (18,525ft) Condoriri and the 6427m (21,080ft) Ancohuma . You can ski at the world's highest developed ski run atop a glacier on the slopes of Chacaltaya, near La Paz, or at nearby but less-developed areas on Condoriri and Mururata. Cycling and river rafting is also popular in Bolivia.
      When you've exhausted the mountains, jungle treks in the Amazonian Basin can be arranged in Rurrenabaque, El Porvenir (in the Reserva Biosférica del Beni), Perseverancia (in the Preseverancia and Reserva de Vida Salvaje Ríos Blanco y Negro) and in the remote but pristine Parque Nacional Noel Kempff Mercado in the northernmost reaches of Santa Cruz Department. River boats plying the Río Mamoré from Trinidad go into the heart of Bolivia 's greatest wilderness area, enabling travelers to experience the mystique and solitude for which the Amazon is renowned. And there is Bird watching among activities in Bolivia .