Salar de Uyuni, the mirror-like salt sea of the Bolivian Altiplano

Salar de Uyuni near Uyuni in Bolivia spreads as a vast high-altitude salt crust that turns the Andean sky into a mirror-like second horizon.

On the Bolivian Altiplano near Uyuni, Salar de Uyuni spreads as a vast salt crust that, in certain conditions, turns the Andean sky into a mirror-like second horizon. Rising at around 3,656 m (11,995 ft) above sea level in southwest Bolivia, this high plateau salt flat combines extreme scale with striking flatness in a way few landscapes match.

A continental-scale sheet of salt

Salar de Uyuni occupies a broad basin in the central Andes, part of the Altiplano that forms a high plateau between the Cordillera Occidental and Cordillera Oriental mountain chains. The salt flat covers about 10,582 km² (4,085 sq mi), creating a horizontal expanse comparable in size to a small country and making it widely described as the largest salt flat on Earth.Uyuni Salt Flat area

The surface of Salar de Uyuni is formed by a crust of halite and other evaporite minerals, resting over a brine-rich subsurface. Studies and travel accounts describe salt volumes of several billion tonnes, with the crust in the central areas reaching thicknesses of up to around 10 m (33 ft) above underlying sediments.layers of salt and depth Across much of its area the salt surface is remarkably flat, creating long sightlines in every direction and a continuous pale ground that extends to distant volcanic ridges.

Ancient lakes and lithium-rich brine

Geological research places Salar de Uyuni within a chain of Quaternary lake basins that once filled much of the southern Bolivian Altiplano. The salt flat is a remnant of extensive palaeolakes such as Lago Minchin and Lake Tauca, whose evaporation left thick sequences of salt and mud layers in enclosed depressions.Quaternary geochemical evolution Beneath the white crust, boreholes intersect saline pan deposits stacked with evaporite beds and mud, marking repeated cycles of flooding and drying within the basin.evaporitic sequence beneath the flat

The brine under Salar de Uyuni is notable for its lithium content, and published estimates attribute a substantial share of known lithium reserves to this single basin.lithium-rich brine beneath the crust Alongside lithium, the brine carries potassium, magnesium and boron, reflecting the long concentration of dissolved minerals in a closed drainage system with no outlet to the sea.USGS description of wet playa deposits What visitors see on the surface is the final crystallised layer of this multi-metre-thick evaporite body, patterned by natural polygonal ridges where salt plates meet.

Light, reflection and islands of volcanic rock

One of the most striking aspects of Salar de Uyuni is the way it interacts with light. In dry conditions, the crust forms a matt, bright white surface that reflects sunlight and makes the horizon difficult to distinguish. After rainfall, shallow sheets of water can cover areas of the flat, turning sections into a near-continuous mirror that reflects clouds, stars and surrounding volcanoes in a symmetrical plane. The high elevation and clear Altiplano air contribute to long views across the basin towards peaks such as Tunupa, a volcano rising from the northern shore.

Amid the salt, several rocky islands emerge as local high points, composed largely of older volcanic and sedimentary materials that predate the present salt crust.description of islands and geology These islands carry cacti and other hardy vegetation adapted to the high-altitude climate, and they give visitors a vantage point from which to appreciate the scale of the surrounding flat. From such elevated spots, the salt pan reads as a solidified inland sea bordered by distant Andean summits.

Visiting Salar de Uyuni: what travellers from Western Europe should know

• Salar de Uyuni lies in southwest Bolivia’s Potosí Department, on the Altiplano north-west of the town of Uyuni, reached by road from regional centres such as Potosí.
• The salt surface is exposed, high and open, with travel often crossing compacted salt and sections of shallow water; the altitude around 3,656 m (11,995 ft) can be demanding for those unaccustomed to high plateaus.
• The official language is Spanish and the currency is the Boliviano.
• Entry requirements depend on your nationality; UK travellers can check the FCDO travel advice at gov.uk/foreign-travel-advice, Irish travellers the Department of Foreign Affairs at ireland.ie.

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Frequently asked questions about Salar de Uyuni

Where is Salar de Uyuni in relation to Uyuni?

Salar de Uyuni lies on the Bolivian Altiplano in southwest Bolivia, extending north-west from the town of Uyuni into Potosí Department.

What can visitors expect when they reach the salt flat?

Visitors encounter a broad, pale salt crust at high altitude, with long sightlines, occasional shallow water that creates reflective surfaces and rocky islands rising from the flat.

What makes Salar de Uyuni distinctive among landscapes?

Its combination of altitude, near-level salt surface, large area and the presence of lithium-rich brine beneath the crust gives Salar de Uyuni a character that is both geological and visual.