Cerro Tronador (3,491m), Ventisquero Negro & Cascada Los Alerces Day-Trip Guide

Ninety kilometres south-west of San Carlos de Bariloche on the border between Argentina and Chile rises the undisputed monarch of Parque Nacional Nahuel Huapi: the extinct stratovolcano Cerro Tronador (3,491 metres / 11,453 feet). Crowned by seven active glaciers across its three summits (Argentino, Internacional, and Chileno), the mountain was named Tronador ("The Thunderer") because the booming crack of giant seracs calving off its upper ice cliffs echoes through the valley like summer thunder.

1. Ventisquero Negro (The Black Glacier) & Garganta del Diablo

Turning west off paved Ruta Nacional 40 at Villa Mascardi (35 km south of Bariloche), scenic gravel Ruta Provincial 82 winds along the shores of Lago Mascardi and the milky-blue Río Manso Superior through Pampa Linda to the base of Tronador:

• How a White Glacier Turns Pitch Black (Ventisquero Negro): At the viewing platform two kilometres before the end of the road, you stand directly in front of one of Patagonia's strangest geological phenomena: the Ventisquero Negro. High above on the 3,491-metre summit gleams the immaculate white Glaciar Manso. As blocks of white ice avalanche 700 metres down a sheer volcanic rock cliff into the valley floor, they mix thoroughly with dark basalt rubble, volcanic sand, and moraine mud, reconstituting at the bottom into a slow-moving, soot-black glacier tongue that calves dark-striped icebergs into its terminal meltwater lagoon.
• Garganta del Diablo Amphitheatre: Two kilometres past Ventisquero Negro at the end of the road, a short flat walk leads to the base of the Garganta del Diablo, a sheer semicircular basalt canyon wall down which dozens of glacial meltwater ribbons plunge from the upper ice cap. Experienced hikers can also trek from Pampa Linda up to the mountain hut of Refugio Otto Meiling (2,000m) perched between the Castaño Overo and Manso glaciers.

2. Cascada Los Alerces & Crucial One-Way Mountain Road Hours

• The Southern Fork to Cascada Los Alerces: At the Los Rápidos bridge on the Río Manso, the southern fork (Ruta Provincial 81) winds past Lago Los Moscos and Lago Hess through dense coihue woods to a wooden boardwalk looking out over the thundering twenty-metre Cascada Los Alerces canyon waterfall.
• Respect the Strict One-Way Road Schedule (Mano Única): Because the forty-kilometre gravel mountain road from Villa Mascardi to Cerro Tronador and Cascada Los Alerces is narrow and winding, National Park rangers enforce strict one-way traffic windows every day: uphill entry Only in the morning (typically 10:30 to 14:00) and downhill exit only in the late afternoon (typically 16:00 to 18:00), with two-way traffic permitted only after 19:30; verify current seasonal gate hours with Nahuel Huapi National Park before departing Bariloche by rental car.