You may not have heard of Uyuni, but our astronauts have. It is used as a target for calibrating and testing remotes sensing systems on satellites in orbit. Why? It is big - very big - and has an incredibly smooth surface which is highly reflective when it is covered in water, making it perfect for that task.
http://trifter.com/caribbean-latin-america/bolivia/the-spectacular-sea-of-salt-salar-de-uyuni/
From the Upcoming ueue, submitted by taliesyn30.
check it out on googlemaps