The Paso de Los Patos is an Andine mountain pass between Argentina

Argentina

Argentina , officially the Argentine Republic , is the second largest country in South America by land area, after Brazil. It is constituted as a federation of 23 provinces and an autonomous city, Buenos Aires...

 and Chile

Chile

Chile ,officially the Republic of Chile , is a country in South America occupying a long, narrow coastal strip between the Andes mountains to the east and the Pacific Ocean to the west. It borders Peru to the north, Bolivia to the northeast, Argentina to the east, and the Drake Passage in the far...

, used by the main column of the Army of the Andes

Army of the Andes

The Army of the Andes was a military force created by the United Provinces of the Río de la Plata and mustered by general José de San Martín in his campaign to free Chile from the Spanish Empire...

 to cross the Andes in early 1817, in order to liberate Chile from Spain. It is located to the interior of the town of Putaendo

Putaendo

Putaendo is a city and commune in the San Felipe de Aconcagua Province of central Chile's Valparaíso Region.-History:Before the arrival of the Spanish conquistadors, Putaendo was a very old town of hunters and gatherers. The Spanish were attracted to gold mines discovered in the outskirts of town...

, to the north of the city of San Felipe

San Felipe, Chile

San Felipe is a commune and the capital city of the San Felipe de Aconcagua Province in central Chile's Valparaíso Region. It is located north of the national capital of Santiago...

, Valparaíso Region

Valparaíso Region

The V Valparaíso Region is one of Chile's 15 first order administrative divisions.Valparaíso Region, 2006 With the country's third highest population of 1,539,852 million in 2002 and third smallest area of , the region is Chile's second most densely populated after the Santiago Metropolitan Region...

, Chile, and framed by the imposing Valle de Los Patos Sur (Southern Valley of Ducks), SW of the Province of San Juan, Argentina. Other names are used for the same pass: the passages of Llaretas, Ortiz, the Honda and the Valle Hermoso.