The Perito Moreno Glacier is a glacier located in the Los Glaciares National Park in the south west of Patagonia, Argentina.
The 100 sq mi ice formation, and up to 20 mi in length, the Perito Moreno Glacier is one of only three Patagonian glaciers that is growing. The terminus of the Perito Moreno Glacier is 3 mi wide, with an average height of 240 ft above the surface of the water of Lake Argentino, in Argentina. It has a total ice depth of 560 ft.
Periodically the glacier advances over the Argentine Lake forming a natural dam which separates the two halves of the lake when it reaches the opposite shore. With no escape route, the water-level on the Brazo Rico side of the lake can rise by up to 100 ft above the level of the main lake. The pressure produced by the height of the dammed water finally breaks the ice barrier holding it back, in a spectacular rupture event.
This dam/rupture cycle is not regular and it recurs naturally at any frequency between once a year to less than once a decade, but it ruptures, on average, about every four to five years.
Due to its size and accessibility, Perito Moreno is one of the major tourist drawcards in southern Patagonia. It is less than two hours by bus from El Calafate, and many tour companies run daily visits to admire this huge structure.