The North Yungas Road runs 64 kilometres from the high altiplano down through cloud forest to the subtropical valley town of Coroico, dropping 3,500 metres in the process. When it was the only road connecting La Paz to the Yungas lowlands, trucks and buses shared a single-lane track cut into vertical cliffsides with no guardrails and regular patches of fog. Vehicles went over the edge with some regularity. Since a new, safer road was completed in 2006, the old route carries almost no vehicle traffic and has become one of the most popular adventure tourism activities in Bolivia.
Most operators pick you up from your hotel in La Paz at around six in the morning, drive you up to La Cumbre pass at 4,700 metres (where it is cold and sometimes snowing), and hand you a mountain bike for the descent. The ride itself takes four to five hours depending on the group's pace. The first section is paved and fast; the second section, once you drop onto the original dirt road, narrows to three metres wide with vertical drops of several hundred metres on one side. The scenery changes from bare altiplano at the top to dense cloud forest by the bottom. Operators vary significantly in equipment quality and guide experience. Gravity Bolivia and Barracuda have consistently good reputations; avoid any operator that hands you a bike without testing the brakes and adjusting the seat. You will be back in La Paz by early evening, significantly muddier than you left.