Lago Pirihueico is a stunning glacial lake tucked deep in the Andes of Chile's Los Ríos Region, approximately 68 kilometers southeast of Panguipulli in the Panguipulli Commune of Valdivia Province. Stretching 23 kilometers in length and roughly 2 kilometers wide, this elongated lake sits at an elevation of 586 meters and reaches a maximum depth of 145 meters, with an average depth of approximately 62 meters and a total water volume of 1.88 cubic kilometers. The lake occupies a geological fault line shared with Lago Panguipulli and Argentina's Lago Lácar, and is fed primarily by the Río Hua-Hum, which drains Lago Lácar from Argentina. Its outflow is the Río Fuy, which connects downstream through a chain of lakes ultimately reaching the Pacific Ocean via the Río Valdivia. The lake's glacial origins contribute to its famously pristine, blue-green waters and exceptional clarity. The surrounding landscape is dominated by native Valdivian temperate rainforest, including coigüe (Nothofagus dombeyi), mañío (Podocarpus nubigenus), notro (Embothrium coccineum), and ulmo, with the southern shoreline falling within the Huilo Huilo Biological Reserve. Lago Pirihueico is one of the celebrated Seven Lakes of the Panguipulli Commune and serves as an important waterway for travelers crossing to Argentina via the Huahum Pass.