The "island" of fossilized coral, covered in ancient cacti that grow only a centimeter a year. It's not an island in the strictest sense, just a big rock sticking up out of the otherwise flat ground, but the salt near the edge of it looks strikingly like water coming up to the shore. The island has a hiking trail to the top, for truly surreal views of the salar. It also has a restaurant, and lunch is eaten by most tour groups on the western "shore" of this island. There are well-maintained restrooms.