Río Agrio winds through one of the most dramatic and remote corners of Argentine Patagonia, flowing through the volcanic landscape near the town of Caviahue in the province of Neuquén. Situated at the foot of the Copahue volcano at approximately 1,600 meters above sea level, this river is surrounded by ancient Araucaria forests, turquoise-colored lagoons, and small waterfalls — a setting that makes it as visually stunning as it is productive for fishing. The river moves through corridors and pools, sliding slowly through the landscape in a way that creates ideal holding water for trout throughout the season. Its crystal-clear waters and pristine Andean environment make it one of Patagonia's most compelling destinations for the traveling angler.