The largest mirror of the earth broken by science

IThe southwest of Bolivia, near the border with Chile, lies what is commonly called “the largest natural mirror in the world”. When it rains on the huge salted tray called Uyuni Salar, tourists flock from around the world to pose for photos, in the hope of capturing themselves, their vehicles and the mountains, the clouds and the surrounding sky perfectly reflected in dreamlike mirror scenes.

Although it is not really a perfect mirror. According to researchers who studied the area using satellite images, ground measures and drone data. They reported their overwhelming discoveries in Earth & Environment Communications recently.

Scientists have found that if the ephemeral and shallow lake that trains in Salar de Uyuni is exceptionally smooth and calm, it does not behave like a mirror, according to satellite data. Especially in the interior parts that tourists cannot reach. For a surface to behave like a mirror, variations in its surface should generally be smaller than a wavelength of visible light. The research team has analyzed more than 390,000 radar measures – where the water signals shooting satellites in water in flat salt and measure the softness of the signal that bounces – collected during about 8 years. Scientists have concluded that the sweetness and reflectivity of the salt vary over time and through the extent of the surface.

To confirm their remote sensing measures, scientists collected data in the field last year in Salar de Uyuni. They used an optical tool to characterize the surface of the lake, combining this measurement with similar optical data of drones flying above the head.

It turns out that the surface of the lake is far from uniform. On its surface of 3,800 square miles, some patches hit the environmental conditions. Remarkably, however, few waves are formed on the gigantic lake, even if the winds push the water. The researchers suggest that the superficiality of the temporary lake – it represents on average less than an inch deep – and the presence of salt crystals on the surface helps keep water so calm.

Although its perfect mirror has failed to resist a strict scientific examination, Salar de Uyuni is always a wonder. After a good rain, it is a dazzling reflection of the ability of the earth to inspire and surprise.

Lead image: Dessizned / Shutterstock

• Bob Grant

  Published on September 26, 2025

  Bob Grant is the editor -in -chief of Nautilus.