Salar de Uyuni in the context of "Potosí Department"

Natural salt pans or salt flats are flat expanses of ground covered with salt and other minerals, usually shining white under the sun. They are found in deserts and are natural formations (unlike salt evaporation ponds, which are artificial).

A salt pan forms by evaporation of a water pool, such as a lake or pond. This happens in climates where the rate of water evaporation exceeds the rate of precipitation — that is, in a desert. If the water cannot drain into the ground, it remains on the surface until it evaporates, leaving behind minerals precipitated from the salt ions dissolved in the water. Over thousands of years, the minerals (usually salts) accumulate on the surface. These minerals reflect the sun's rays and often appear as white areas.

The Altiplano (Spanish for "high plain"), Collao (Quechua and Aymara: Qullaw, meaning "place of the Qulla") or Andean Plateau, in west-central South America, is the most extensive high plateau on Earth outside Tibet. The plateau is located at the latitude of the widest part of the north–south-trending Andes. The bulk of the Altiplano lies in Bolivia, but its northern parts lie in Peru, its southwestern fringes lie in Chile, and it extends into Argentina.

Many towns and several cities are on the plateau, including El Alto and Oruro in Bolivia and Juliaca and Puno in Peru. The northeastern part of the Altiplano is more humid than the southwestern part, which has several salares (salt flats), due to its aridity. At the Bolivia–Peru border lies Lake Titicaca, the largest lake in South America. Farther south, in Bolivia, Lake Poopó existed until recently, but by December 2015, it had completely dried up, and was declared defunct. Whether that lake, which had been the second-largest in Bolivia, can be restored is unclear.

A dry lake bed, also known as a playa (/ˈplaɪ-ə/), is a basin or depression that formerly contained a standing surface water body, which disappears when evaporation processes exceed recharge. If the floor of a dry lake is covered by deposits of alkaline compounds, it is known as an alkali flat. If covered with salt, it is known as a salt flat.