The Uyuni salt lake of Tunupa, covers km², making it the biggest salt lake in the world. It is located metros up in the mountains of Bolivia, and is considered as one of the seven natural marvels of the world.

After rain when covered with water the salt lake is converted into the largest mirror in the world.

It is comprised of approximately 11 layers of salt of depths varying from 2 to 10 meters. The superficial crust is about 10 meters deep while the maximum depth of the salt lake is 120 meters. The crust is comprised of mushy salt brine when wet.

The salt lake of Uyuni, is estimated to contain 10 thousand million tonnes of salt, of which they extract 25 thousand tonnes each year.

The traditional extraction method is to make mounds from which the water evaporates before transporting.

These blocks of dry salt are used in construction of hotel buildings on the salt lake.