The Río Grande in Mendoza, Argentina is a long, remote whitewater river that originates high in the Andes near the Las Leñas ski resort and flows generally southward through arid basalt canyons before joining the Río Barrancas to become the Río Colorado. The river is accessed via the city of Mendoza or the smaller city of San Rafael, located roughly three hours south of Mendoza. San Rafael, with a population of around 200,000, serves as the primary staging point for expeditions.

The river runs approximately 190 miles of class III-IV whitewater with one mandatory portage and one class V rapid, dropping from roughly 7,200 feet to about 2,600 feet in elevation. A good access point exists at the midpoint of the trip, allowing paddlers to split the journey into an upper "Grande" section and a lower "Grande-Colorado" section. One expedition completed this stretch in 14 days. Beyond the main whitewater section, it is also possible to continue an additional 130 miles of easier river through open desert landscape, including one class II canyon, before reaching the first dam impoundment.

The river passes through remote basalt canyon terrain with little infrastructure, making it a true multi-day expedition. Camps are established on beaches along the river. Water levels are influenced by Andean snowmelt, and late spring and early summer align with viable flows. Abnormally low flows can reduce available time on the water.

The canyon scenery is a defining feature of the experience, and the river has been considered for UNESCO World Natural Heritage Site designation. The entire river system faces a significant threat from proposed dam construction, which has been a subject of ongoing political and environmental controversy; a dam project was approved by both the federal and Mendoza provincial governments in early 2018 despite opposition.

Other paddling options in the broader region include the Río Atuel, Río Mendoza, Río Tunuyán, and Río Diamante, which range from class II to class V and are generally more accessible as day trips from San Rafael or Mendoza.