Lago Argentino is a lake in the Patagonian province of Santa Cruz, Argentina, at 50°2′S 72°4′W / 50.033°S 72.067°W / -50.033; -72.067. It is the largest freshwater lake in Argentina, with a surface area of 1,415 km (546 sq mi) and a maximum width of 20 mi (32 km). The lake's waters have an average depth of 155 m (509 ft), with a maximum depth of 719 m (2,359 ft). The deepest point of the lake is situated; in the end of its narrow north-northwestern arm. In front of the retreating Upsala Glacier. This depth was discovered during a survey in, 2001. The south-southwestern arm ends in front of the, Perito Moreno Glacier. The glaciers debouches into the lake at these sites. Making "trenches" in the bedrock. The lake reaches, astonishing 541 m (1,775 ft) below mean sea level.

Lago Argentino lies within Los Glaciares National Park, in a landscape accented by numerous glaciers, and the lakes of the area are fed by the glacial meltwater of several rivers. For example, the waters of Lake Viedma are fed by the La Leona River, and many other, smaller mountain streams. Lago Argentino's drainage basin amounts to more than 17,000 km (6,564 sq mi). Water from Lake Argentino flows into the Atlantic Ocean through the Santa Cruz River.

The glaciers, the nearby town of El Calafate, and the lake itself are all important tourist destinations, with many unique hostels, hotels and other amenities catering to the outdoors located in the region. The lake, in particular, is appreciated for fishing. Perch, common galaxias ("puyen grande"), lake trout and rainbow trout—in both anadromous and potamodromous forms—are all found.

Lago Argentino was also the name of the airport that served the area until 2000. This airport is currently closed, and its runway was incorporated into the city's road system. It has since been replaced by Comandante Armando Tola International Airport, which serves the town of El Calafate and Lago Argentino with many national and international flights each day.

Lago Argentino, and its surrounding terrain, is home to numerous living organisms; as of 2024, the biodiversity database iNaturalist lists nearly 500 recorded plant and almost 400 animal species as being found in the area, as well as nearly 100 types of fungi and lichen.

Birds

Around 150 species of birds have been documented in and around the lake. Many are endemic to the region, such as the roughly 50-60 species of wading birds and waterfowl; iconic amphibious species, like Andean and Chilean flamingos, as well as the black-headed duck, black-necked swan, cinnamon teal, crested duck, Coscoroba swan, kelp goose, silver teal, torrent duck and many others can be found here, as well as varied species of coot, cormorant, dotterel, gallinule, godwit, grebe, gull, knot, lapwing, oystercatcher, phalarope, plover, sandpiper, snipe, stilt, tern and yellowlegs.

Other birds include the famous Andean condor (the largest New World vulture), Austral parakeet, Austral pygmy-owl, cinereous harrier, crested caracara, the flightless Darwin's rhea (the largest bird in the area), lesser horned owl, Magellanic woodpecker, and the short-eared owl.

Fish

Puyen (Galaxias maculatus) and perca (Percichthys), are two registered species of fish that live in the lake. Also present are introduced and non-native brown trout (Salmo trutta), chinook salmon (Oncorhynchus tshawytscha), lake trout (Salvelinus namaycush) and rainbow trout (O. mykiss).

Reptiles and Amphibians

Of the roughly 10-15 reptile species recorded in the vicinity of Lago Argentino, the majority of them are lizards (Squamata) of the generas Diplolaemus and Liolaemus, including several species of tree "iguanas", smooth-headed and smooth-throated lizards.

Anurans (frogs and toads) that inhabit the lake include Alsodes coppingeri, the Eden Harbour toad (Nannophryne variegata), the large four-eyed frog (Pleurodema bufoninum), Nibaldo's wood frog (Batrachyla nibaldoi), and the Puerto Eden frog (Chaltenobatrachus grandisonae).

Argentino Lake has a cold desert climate (Köppen BWk).

• 
  Argentino seen from the town of El Calafate
• 
  Lake Argentino as seen from the road to Los Glaciares National Park
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  Base of Perito Moreno glacier
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  Iceberg and tourist boat on the lake

• Lake Viedma
• Lake San Martín
• Puerto Bandera

• Lake Argentino on the website of the International Lake Environment Committee Foundation
• Lago Argentino on the website of the government of Santa Cruz (in Spanish)
• Lago Argentino Airport at World Airport Codes and ICAO World Airfield Catalogue