The Río Negro in the Los Lagos Region of southern Chile is one of the principal tributaries of the Rahue River, originating in the Coastal Precordillera and draining part of the eastern slopes of Cordillera Pelada as it flows from south to north. Its confluence with the Rahue sits at an elevation of approximately 26 meters. The commune of Río Negro takes its name from this river.

The section of the Río Negro near Hornopirén is known to kayakers for its steep basalt drops, giving it a notably different character from the nearby Río Blanco, which features smooth granite boulders and glacial meltwater. The two rivers run only a few miles apart in the Hornopirén area but present distinctly different paddling experiences. Hornopirén itself is accessible from Puerto Montt via a combination of road and small ferry, and it is considered the gateway to Patagonia.

The steep basalt drops indicate that this is a technically demanding river, and paddlers should be prepared for committing whitewater. Beyond this general characterization, specific details on access points, portages, seasonal flow levels, water temperature, and facilities are not well documented, so thorough on-the-ground scouting and consultation with local outfitters in the Hornopirén area is advisable before attempting a descent.