Los Glaciares, of which 30% is covered by ice, can be divided in two parts, each corresponding with one of the two elongated big lakes partially contained by the park. Lake Argentino, and the largest in Argentina, is in the south, while Lake Viedma,, is in the north. Both lakes feed the Santa Cruz River that flows down to lower part Puerto Santa Cruz on the Atlantic. Between the two halves is a non-touristic zone without lakes called Zona Centro. The northern half consists of part of Viedma Lake, the Viedma Glacier and a few minor glaciers, and a number of mountains very popular among fans of climbing and trekking, including Mount Fitz Roy and Cerro Torre. The southern part has, as well as a number of smaller ones, the major glaciers which flow into Lake Argentino: Perito Moreno Glacier, Upsala Glacier, and Spegazzini Glacier. Typical excursion boats travel between icebergs to visit Bahía Onelli, and the otherwise inaccessible Spegazzini and Upsala. Perito Moreno is reachable by land.
Climate
The park has a cool and moist temperate climate. Mean temperatures range from in winter to in summer although at higher altitudes, the mean annual temperature can be around. The park receives an average annual rainfall of in the west and in the east which is evenly distributed throughout the year. Snowfall is common during the colder months.
Ecology
The mountains hold most of the humidity from the Pacific Ocean, letting through only the ice coldness and creating the arid Patagonian steppe on the Argentine side of the range. This area is habitat for ñandúes, guanaco, cougar, and South American gray fox, the latter of which has suffered from the invasion of the cattle industry and are endangered. The guanaco, while not endangered, has had a dramatic decline in historic population due to large scale grazing of livestock throughout much of Patagonia. There are over 100 species of birds in the area. Between the ice and the Patagonian steppe there is a fertile area of Magellanic subpolar forests composed mainly of lengas and guindos, but also ñires. Within these more hospitable areas also live huemul deer and torrent duck.
Issues
Los Glaciares National Park faces many issues around tourism, overgrazing, forest fires and more. There are areas of the park where overgrazing is quite a problem and contains many alien/invasive and feral species such as cattle, European hares and certain types of trout. Forest fires have had a strong impact on the site and degraded and destroyed parts of it as well.
Human use
Los Glaciares is a major attraction for international tourists. Starting points of tours are the village of El Calafate at the shore of Lake Argentino but outside the park, where the park's administration has its headquarters, and El Chaltén village in the northern part of the park, at the foot of the Fitz Roy. Other touristic points in the park include Lago del Desierto and Lago Roca.
