Tronador, Stratovolcano in southern Andes, Chile

Tronador is an extinct stratovolcano on the Argentina–Chile border whose highest peak, the Internacional or Anon, reaches 3,478 m. Two lower summits, the Argentino and Chileno peaks, flank it. The upper part is snow and ice; the lower slopes are forested.

Hermann Claussen reached the summit on January 29, 1934, becoming the first person to stand on the highest point and spending the night there. Before him, several expeditions had tried to reach the top but failed due to technical difficulties and changing weather conditions.

The name refers to the sounds of ice blocks breaking away from the glaciers and crashing into the valleys below. Hikers often hear this thunder during their visits on clear days.

Access is from Bariloche via Route 40 in Argentina or from Puerto Montt through Lake Todos los Santos in Chile. The best time to visit is between December and March when trails have less snow and the weather is more stable.

Ventisquero Negro is a reconstituted glacier at the base of Tronador, fed by the Río Manso Glacier several hundred metres higher. Its dark brown colour comes from dirt and sediment picked up in the accumulation zone, not from volcanic rock. Brown icebergs calve into a small lake and melt there.