Lake Titicaca is the world's highest lake navigable to large vessels, lying at 3,810m above sea level in the Andes Mountains of South America, astride the border between Peru to the west and Bolivia to the east. Titicaca is the second largest lake of South America (after Maracaibo).

It covers some 8,300 square km and extends in a northwest-to-southeast direction for a distance of 190 km. It is 80 km across at its widest point. A narrow strait, Tiquina, separates the lake into two bodies of water.

The smaller, in the southeast, is called Lake Huinaymarca in Bolivia and Lake Pequeno in Peru; the larger, in the northwest, is called Lake Chucuito in Bolivia and Lake Grande in Peru.

The meaning of the name Titicaca is uncertain, but it has been variously translated as Rock of the Puma or Crag of Lead. Titicaca lies between Andean ranges in a vast basin (about 58,000 square km in area) that comprises most of the Altiplano (High Plateau) of the northern Andes. In the snow-covered Cordillera Real on the northeastern (Bolivian) shore of the lake, some of the highest peaks in the Andes rise to heights of more than 6,400 m.

The lake averages between 140 and 180 m in depth, but the bottom tilts sharply toward the Bolivian shore, reaching its greatest recorded depth of 280 m off Isla Soto in the lake's northeast corner.