Briny flats, spiny isle

Isla Incahuasi is one of many 'islands' on the high Andean salt 'sea' called Salar de Uyuni. This unusual landscape in Bolivia is a 4,086-square-mile salt flat, the world's largest, and is covered by a thick salt crust over a brine pool heavy with lithium. Isla Incahuasi is actually the top of an extinct volcano reaching up from the middle of the salt flat and is spiked all over with tall pasacana tree cacti. Far back in its history, Isla Incahuasi was surrounded by water: Roughly 40,000 years ago the area was one gigantic lake, and this ancient volcano was submerged beneath it. That explains the coral-like fossil deposits found scattered on the isle.