A recent scientific study has tested claims about the Bolivian salt flat, Salar de Uyuni, often referred to as the world’s largest natural mirror. Researchers found that while parts of the vast landscape can act as a perfect reflective surface, the mirror effect is not as uniform or consistent as previously believed.
Salar de Uyuni, located in southwest Bolivia, spans over 10,000 square kilometers and draws thousands of visitors each year, especially during the rainy season when its surface reflects the sky in breathtaking detail. Until now, however, this mirror-like phenomenon had not been scientifically verified.
The study, published in Communications Earth & Environment, used a two-part method to investigate the reflective quality of the Bolivian salt flat. First, researchers analyzed more than 390,000 radar signals captured by Sentinel-3 satellites between 2016 and 2024.
These satellites use radar altimeters to measure the smoothness of Earth’s surface. A strong signal bounce-back indicated a smoother, more mirror-like surface.
Field data matches satellite findings
To validate the satellite data, the research team conducted field tests in February 2024, during peak wet season. The visit was timed to match a satellite pass overhead.
On-site, scientists used optical equipment to measure the water’s surface and deployed drones to capture images of sunlight reflections. The visual data confirmed the radar readings, showing that a strong return signal accurately indicated a reflective surface.
Despite the strong visual impressions from tourist photos, researchers concluded that the salt flat does not behave as a uniform mirror. The study found that smooth, reflective conditions only occur under specific weather circumstances—particularly after heavy rainfall and before significant evaporation begins. These conditions are most likely to appear between late January and early March.
Climate and water depth influence reflection
One of the study’s surprising discoveries was the minimal effect of wind on the mirror surface. While wind typically disturbs water surfaces, scientists found that the water on the salt flat is too shallow to form ripples, even during breezy conditions. This allows the reflection to remain largely undisturbed.
Researchers noted that although the Bolivian salt flat can display remarkable mirror-like qualities, these conditions are temporary and vary across different areas. The reflection depends largely on short-term climate patterns and terrain irregularities.
The study brings scientific clarity to a popular natural wonder and offers a deeper understanding of why and when the mirror effect occurs. For visitors hoping to experience it, the best viewing window remains late January through early March, when rainfall levels are highest and the surface remains undisturbed.
