Lago Pellegrini is an artificial reservoir located in the General Roca Department of Río Negro Province, in Argentine Patagonia, near the city of Cinco Saltos. It sits at approximately 270 meters above sea level at coordinates 38°40′S 68°00′W. The lake covers 112 km² with an average depth of 9.4 meters and a maximum depth of 18 meters, holding a volume of roughly 1.053 billion cubic meters.

The reservoir originated as a natural wind-eroded depression that was subsequently filled via a derivation channel drawing water from the Neuquén River. That canal runs approximately 120 kilometers and also supplies the irrigation network of the Alto Valle region. The Dique Ingeniero Ballester dam is the source structure for this canal system.

Access to the lake is straightforward: it lies about 14 kilometers off National Route 151, which connects the region to the south. The balneario (beach and recreation area) includes camping facilities, restrooms, and parrillas (grilling areas), making it a practical base for paddlers spending a day or a weekend on the water.

Paddling activities at the lake include kayaking, canoeing, sailing, windsurfing, and kitesurfing. The lake's large open surface area — over 100 km² — and the dry Patagonian climate mean that wind is a consistent presence, which benefits sail-based sports but warrants attention for kayakers and canoeists who should be prepared for open-water wind exposure.

The surrounding landscape is characteristic of Patagonian steppe — arid and flat — with the lake presenting a striking contrast as a large body of open water in an otherwise desert environment. The area supports a notable variety of bird species, making wildlife observation a secondary draw for those on the water. Fishing for pejerrey and trout is also practiced on the lake.

Summer is the primary season for water-based recreation, with the dry and mild climate of the Alto Valle making warm-season visits the most practical. The lake is ranked as the top attraction in Cinco Saltos on major travel platforms, reflecting its regional significance as a recreational destination.