Those hexagons are not decoration. They are physics made visible. As water near the salt's surface evaporates, it grows saltier and therefore heavier, and it sinks, while less salty water rises from below to take its place. This slow churning organizes itself into convection cells, packed together until their boundaries form a hexagonal grid, the same efficient shape that bees and basalt and drying mud all converge upon. Where the salt crystallizes at the surface, it builds up along those cell edges into low ridges, tracing the hidden circulation beneath. Walk the flat and you are reading a map of forces you cannot see, written in crystal across 212 square kilometers of desert.

The Salinas Grandes change character with the weather. In the dry months the crust is a brilliant, cracked-tile expanse, dazzling enough to demand sunglasses and to fool the eye into seeing water where there is only salt. After rain, a thin sheet of standing water can turn the entire flat into an enormous mirror, the sky and the surrounding mountains doubled in perfect reflection until the line between earth and heaven dissolves. National Route 52 runs straight across the salt, carrying travelers toward the Paso de Jama and the Chilean border beyond, a ribbon of road laid over one of the strangest surfaces on the continent.

The flat is not empty of human life. Around the Salinas Grandes and the neighboring Guayatayoc lagoon live some 33 communities of Kolla and Atacama people, who have worked this landscape for generations. They herd small livestock, farm at the margins, make crafts, and harvest the salt itself in a traditional, cooperative way, prying it from the surface much as their ancestors did. Their relationship with this harsh place is intimate and old, built on a careful understanding of where the scarce water lies and how the seasons turn at altitude. The salt is not scenery to them. It is livelihood, heritage, and home.

Beneath the white crust lies something the modern world craves. The brine under the Salinas Grandes is rich in lithium, the metal at the heart of the batteries powering phones and electric cars, and this flat sits within the so-called lithium triangle alongside Chile's Salar de Atacama and Bolivia's Salar de Uyuni. Extraction, though, demands enormous quantities of water in one of the driest regions on Earth, and that has put miners and communities on a collision course. The 33 Kolla and Atacama communities have resisted lithium projects on their land, citing falling groundwater that threatens their farming and their drinking water, and the violation of their right to decide what happens on territory that has always been theirs. The fight over the salt is, in the end, a fight over water, and over who gets to choose.