the Argentinian side, can be visited from Refugio Otto Meiling, a mountain hut that is sandwiched between it and Castaño Overa Glacier. Castaño Overa, also on the Argentinian side, is smaller and relatively accessible by hike from Pampa Linda. Guided trekking tours allow visitors to cross Castaño Overa or walk to Tronador's peak. Ventisquero Negro ("black snowdrift" in Spanish) is a rather unusual glacier at the base of Tronador in Nahuel Huapi National Park. Its unusual dark brown colour comes from dirt and sediment picked up in the glacier's accumulation zone, which is fed by the Río Manso Glacier several hundred metres higher up the mountain. Brown icebergs calve from the glacier and then float in a small lake until eventually melting. Peaks According to the Aoneker map, these are the named peaks on Tronador: Anon or Internacional (3484m), Argentino (3187), Chileno (3262), and Torre Ilse (2585). Named ridges include Filo Sur (3054), Filo Blanco (3146), Filo La Vieja (2715), and Filo Lamotte (2340). Mountaineering and tourism Tronador was first climbed by Hermann Claussen solo on 29 January 1934, after several attempts. A mountain hut, Refugio Otto Meiling, is the destination of popular day hikes on the mountain, and is named after a German mountaineer who made dozens of ascents and spent years guiding people around it. The hut is located about 1200m vertically above Pampa Linda, at the mountain's base. Most summers the Internacional or Anon peaks (the highest of Tronador's three peaks) is climbable. However, an unusually hot summer increased rockfall to dangerous levels during January and February 2008. The Argentine side risks becoming no longer accessible due to increasingly warm weather in the region destabilising the glaciers. See also Cerro Volcánico Bariloche Gallery References Stratovolcanoes of Chile Stratovolcanoes of Argentina Andean Volcanic Belt International mountains of South America Subduction volcanoes Volcanoes of Río Negro Province Volcanoes of Los Lagos Region Mountains of Los Lagos Region Nahuel Huapi National Park Argentina–Chile border Extinct volcanoes Pleistocene stratovolcanoes Pleistocene South America Three-thousanders of the Andes