Lake Titicaca lies about 3,810 meters above sea level.

The lake occupies the high Andean plateau known as the Altiplano. Its great altitude places a large expanse of freshwater in a setting more often associated with mountain slopes and cold upland grasslands.

At roughly 8,300 square kilometers, Titicaca is South America's largest freshwater lake by surface area. That qualification matters because comparisons with coastal lagoons or differently classified water bodies can produce different rankings.

The quoted elevation is approximate. Rainfall, inflow and evaporation change the amount of water stored in the basin, so the lake does not maintain an absolutely fixed surface height throughout every season or year.

Peru borders the western part of Titicaca and Bolivia the eastern part. The lake extends broadly from northwest to southeast across their shared highland region. The international boundary crosses the water, but it does not divide the lake into separate hydrological systems. Water quality, changing water levels and the health of shoreline wetlands are therefore concerns that extend beyond either country's shore.

Titicaca consists of a larger basin and a smaller basin joined by the Tiquina Strait. This narrow connection is an important part of its geography: the lake is not simply one broad, evenly shaped bowl. Different depths and the restricted passage between basins help explain why a single surface-area figure cannot describe every aspect of the lake's physical character.

The Desaguadero River is its principal surface outflow. The existence of that river distinguishes Titicaca from a completely outlet-free lake such as the Caspian. Nevertheless, evaporation is a major component of its water balance. Identifying an outlet tells us where some water leaves, but not that most incoming water must travel through that channel.

The UNESCO tentative-list submission describes Titicaca as one of the world's relatively few ancient lakes and gives an estimated age of about three million years. This is a statement about the lake's long geological history, not a claim that its shoreline and water level have remained unchanged. A persistent basin can experience substantial changes in size and environmental conditions over time.

Titicaca's high elevation also requires care with popular superlatives. It is frequently called the world's highest navigable lake, but navigability depends on what size of vessel and what kind of service are being considered. Smaller lakes exist at higher elevations. The clearer, more reproducible statement is that Titicaca is a very large freshwater lake with a surface around 3,810 meters above sea level.

The UNESCO page cited here records a tentative-list submission made in 2005. A tentative listing is a proposal by a state party, not the same status as inscription on the World Heritage List. It provides useful descriptive information while requiring that distinction when discussing international recognition.

Titicaca’s altitude is the elevation of a water surface shared by Peru and Bolivia. That is not the depth of the lake, the elevation of every island, or the height of nearby mountains. Its position on the Altiplano places an extensive water body within a high Andean landscape, making it a useful example of how a plateau can contain major basins.