Nahuel Huapi Lake () is a lake in the lake region of northern Patagonia between the provinces of Río Negro and Neuquén, in Argentina. The tourist center of Bariloche is on the southern shore of the lake. The June 2011 eruption of the Puyehue-Cordón Caulle volcanic complex, in neighboring Chile, caused parts of the lake's surface to be blanketed in volcanic ash. During the Last Glacial Maximum of the Llanquihue glaciation the lake basin was wholly occupied by a glacier. Etymology The name of the lake derives from the toponym of its major island in Mapudungun (Mapuche language): "Island of Puma", from nahuel, 'puma', and huapí, 'island'. There is, however, more to the word "Nahuel"—it can also signify 'a man who by sorcery has been transformed to a puma'. Geography Nahuel Huapi lake, located within the Nahuel Huapi National Park, has a surface of , rests above the sea level, and has a maximum measured depth (as of 2007) of . The lake depression consists of several glacial valleys carved out along faults and Miocene valleys that were later dammed by moraines. Its seven branches are named Blest (), Huemul (), de la Tristeza (), Campanario (), Machete, del Rincón and Última Esperanza. It is connected to other smaller lakes such as Gutiérrez, Moreno, Espejo and Correntoso. The deep-blue waters hold a number of islands, most notably with an area of , and Isla Huemul on the south end of the lake. A curious fact about the lake is that, despite being nowhere near any ocean and being at high altitude, it is also home for kelp gull and the blue eyed cormorant (Phalacrocorax atriceps), otherwise strictly marine birds. The lake's crystal clear waters are very susceptible to climate changes and have an average surface temperature of ; this makes it both beautiful and treacherous. Hypothermia is one of the risks bathers must undertake. Kayaking is a popular sport on this and adjacent lakes. The lake is also the starting point of the Limay River. Fauna This lake harbors several introduced, non-native species of trout, including rainbow trout, brown trout and brook trout which attract anglers from the world over. Nahuelito At the beginning of the 20th century, and following an old aboriginal legend, the rumor of a giant creature living in the deep waters of the lake took up. The creature is known locally as Nahuelito. Reported sightings of