The lake known as O'Higgins in Chile and San Martín in Argentina is located around coordinates in Patagonia, between the Aysén del General Carlos Ibáñez del Campo Region and the Santa Cruz Province.
General information
The lake has a surface area of , an elevation of above mean sea level, and a shoreline length of . Viewed from above, the lake consists of a series of finger-shaped flooded valleys, of which are in Chile and in Argentina, although sources differ on the precise split, presumably reflecting water level variability. The lake is the deepest in the Americas with a maximum depth of near O'Higgins Glacier, and its characteristic milky light-blue color comes from rock flour suspended in its waters. It is mainly fed by the Mayer River and other streams, and its outlet, the Pascua River, discharges water from the lake towards the Pacific Ocean at a rate of . The O'Higgins Glacier flows eastwards towards the lake, as does the Chico Glacier. Both of these glaciers are part of the Southern Patagonian Ice Field which extends for approximately in a north–south direction to the west of Lake O'Higgins.
Immigrants did not settle in the arid windy area around the lake until the 1910s, when British, Scandinavians and Swiss started raising sheep for wool.
The most common tourist route for visiting the lake is that between El Chaltén in Argentina and Villa O'Higgins in Chile, including a ferry through the lake on the Chilean side.
Water from O'Higgins/San Martín Lake flows into the Pacific Ocean through the Pascua River.
Names
Being the most irregular of the lakes in the area, consisting of eight well defined arms, the name San Martín is sometimes used to refer only to the Argentine side, and O'Higgins to the four Chilean arms. Both names come from independence heroes José de San Martín of Argentina and Bernardo O'Higgins of Chile, who fought together for the liberation of Chile, and came to be known as Liberators of America together with other South American figures.
The four Argentine arms of the lake, with an area of 521 km2, are named Cancha Rayada, Chacabuco, Maipú and De la Lancha, after battles of General San Martín.