What is the highest navigable lake in the world?

The highest navigable lake in the world is Lake Titicaca.

Lake Titicaca sits high in the Andes on the border between Peru and Bolivia, at roughly 3,812 metres above sea level. It is also South America's largest lake by both surface area and water volume. The lake's elevation makes its navigable waters especially remarkable, although the claim normally refers to large commercial or transport vessels rather than every small high-altitude lake that a boat could enter.

Titicaca is an ancient lake with more than 40 islands, including the famous floating Uros islands. Indigenous communities around its shores have depended on fishing, farming, trade, and boatbuilding for centuries. The lake has no major ocean outlet; most of its water is lost through evaporation, with a smaller amount leaving through the Desaguadero River.

A common mix-up is confusing “highest navigable lake” with “highest lake.” Much smaller lakes exist at far greater elevations, including crater lakes on high volcanoes. Titicaca is the standard answer because it is exceptionally large and supports substantial navigation.