Lake Titicaca lies on the Peru-Bolivia border and is often called the world’s highest navigable lake.
The lake sits high in the Andes at roughly 3,812 metres above sea level. Its western section belongs to Peru and its eastern section to Bolivia, with the narrow Strait of Tiquina connecting its two major sub-basins. Puno and Copacabana are among the best-known settlements on its shores.
The phrase “highest navigable lake” usually refers to a large lake used by commercial or substantial vessels. It is not the highest lake of any kind: tiny crater lakes and remote high-altitude lakes occur at greater elevations. Titicaca is also slightly brackish rather than perfectly fresh, despite commonly being described as a freshwater lake.
The lake has long supported Andean communities, including the Uros, who traditionally built floating reed islands from totora. Its waters and islands are also important in regional history and mythology. Lake Poopó, another Bolivian lake, is a separate and much shallower body of water, not the answer to this question.