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.