The Mendoza River, flowing east from the Andes through the Potrerillos canyon about 40 kilometres from the city, offers some of the best accessible white-water rafting in South America. The standard section used by day tours runs through Class III and IV rapids — challenging enough to be genuinely exciting, manageable enough for first-timers with guides. The river is at its highest and most dramatic from October to December when Andean snowmelt is at its peak.
Several tour operators in Mendoza city run day trips to Potrerillos for rafting, with morning departure, the river section, lunch, and return to the city included. Most don't require previous experience, though stronger swimmers tend to enjoy it more. Children above a certain age (usually 12, depending on operator) are accepted.
The Potrerillos reservoir behind the dam that controls the upper section of the river is also popular for kayaking on calmer days. The valley itself, in the foothills of the Andes, is worth the drive regardless of whether you get on the water.