The lake known as O'Higgins in Chile and San Martín in Argentina is located around coordinates 48°50′S 72°36′W / 48.833°S 72.600°W in Patagonia, between the Aysén del General Carlos Ibáñez del Campo Region and the Santa Cruz Province.
Location: O'Higgins Commune, Capitán Prat Province, Aysén del General Carlos Ibáñez del Campo Region, Chile / Lago Argentino Department, Santa Cruz Province, Argentina
Primary inflows: Mayer River
Primary outflows: Pascua River
Catchment area: 12,895 km² (4,979 sq mi)
Basin countries: Argentina, Chile
Surface area: 1,013 km² (391 sq mi)
Average depth: 68 m (223 ft)