Salar de Uyuni: the salt desert that becomes the world's largest mirror

Some photos look fake: people walking on clouds, a car floating in the middle of the sky, a horizon that vanishes. It isn’t Photoshop. It is the Salar de Uyuni in Bolivia during the rainy season. This white desert is one of the strangest and most photogenic landscapes on the planet.

The largest salt flat in the world

The Salar de Uyuni lies in southwestern Bolivia, on the Andean high plateau, at about 3,650 meters above sea level. Covering more than 10,000 square kilometers, it is the largest salt flat in the world. To put that in perspective, it is bigger than many small countries, and from its center all you can see is a white plain stretching to the horizon.

Its origins go back thousands of years. The area was once covered by large prehistoric lakes. When the climate changed and the water evaporated, it left behind huge deposits of salt and minerals. Today the salt crust is several meters thick in places, and the flat is estimated to hold billions of tons of salt.

The mirror of the sky

For most of the year the salt flat is a dry, hard, white surface covered in a curious pattern of cells, many of them hexagonal, that form as the salt crystallizes and cracks. But in the rainy season, roughly December through March or April, the magic happens.

A thin layer of water, sometimes only a few centimeters deep, covers parts of the flat. Because the surface is extraordinarily level and the wind is often light, the water stays almost still and reflects the sky like a giant mirror. The horizon disappears, and it is hard to tell where the earth ends and the sky begins.

So flat that satellites use it

One of the most surprising facts about the salt flat is how level it is: across its entire vast surface, the variation in height is only about one meter. That, together with its huge size, its bright surface and skies that are clear for much of the year, is why it has been used to calibrate the altimeters on satellites that measure the height of land and ice from space.

The treasure beneath the salt: lithium

Under the salt crust lies brine, very salty water rich in minerals. Chief among them is lithium, a metal essential for making batteries for phones and electric cars. The Salar de Uyuni is considered one of the largest lithium deposits in the world. Bolivia has launched projects to extract it, although large-scale production has moved slowly and is debated because of its possible impact on water and on local communities.

What to see on and around the salt flat

• Incahuasi Island: a rocky «island» in the middle of the sea of salt, covered with giant cacti, some several meters tall. From the top there is a stunning view of the flat.
• Train cemetery: on the outskirts of the town of Uyuni sit dozens of rusting locomotives and carriages from the early 20th century, relics of the era when the railway carried minerals to Pacific ports.
• Colchani: a small village on the edge of the flat where families extract and process salt by hand.
• Salt hotels: nearby there are lodgings built from blocks of salt, from the walls to some of the tables and beds.
• High-plateau lagoons: to the south, in the Eduardo Avaroa Andean Fauna National Reserve, there are colored lagoons such as Laguna Colorada, home to colonies of flamingos, along with geysers and volcanic landscapes.

The famous perspective photos

The white plain, with nothing to judge distance by, makes possible some very popular visual tricks: a person who seems to climb out of a bottle, a group of friends being «stomped» by a toy dinosaur, or someone holding another person in the palm of their hand. Almost every tour sets aside time for these shots.

Tips if you plan to go

• Altitude: at over 3,600 meters, altitude sickness is common. Acclimatize for a few days, drink water, eat light and take it easy.
• Sun: radiation is very intense because of the altitude and the glare off the salt. Sunglasses, sunscreen and a hat are essential.
• Cold: days can be warm, but temperatures drop sharply at night, sometimes below freezing.
• Pick your season: for the mirror effect, go in the rainy season; to cross the dry flat and reach Incahuasi Island more easily, go in the dry season.
• Choose a responsible operator: tours are done in 4×4 vehicles; pick operators with good reviews and well-maintained vehicles.

A place that looks like another planet

The Salar de Uyuni is a reminder that the Earth still holds places that can fool our eyes. An ancient lake turned into a desert, a desert that becomes a mirror, and a mirror that, for a few hours, lets us walk on the sky.

Abel Maestro Garcia / Wikimedia Commons (Public domain) · source