In a desolate desert in the southwest area of Bolivia is is 3,800 square mile sheet of salt. Essentially they're hexagonal crystals, which are made up by the crystalline nature of the salt. This unbelievable adventure is only achievable during the salt desert's wet season; it is transformed into a lake that is deep enough for a truck or boat to make their way across- being only 6 to 26 inches deep. This shallow lake flawlessly reflects the sky, causing an illusion of an infinite sky when looking both up and down. The sight is said to be especially amazing at night when the stars are out!
https://www.lonelyplanet.com/thorntree/forums/americas-south-america/Bolivia/salar-de-uyuni-tour-3f464a3e-ce1f-43f5-a857-f897b01c5d29?page=1 is a great website that informs you all about visiting and taking organized tours- the Q and A section is very helpful and makes the adventure a more realistic possibility :)