Eastern Pacific High Sea

At the eastern Pacific edge of the Atacama, the cold Humboldt Current moderates what would otherwise be a tropical sea and reinforces the aridity of the land. Marine air forms fog and cloud, but the Andes and the coastal cordillera block moisture from both sides; the South Pacific anticyclone stabilizes the atmosphere. Annual rainfall averages about 15 millimetres, with some stations recording no rain at all. Narrow coastal valleys, springs and oases made settlement possible before later water systems.

The sea supplied fish, birds and other coastal products to Chinchorro populations from roughly 7000 to 1500 BCE. Their sedentary settlements stretched from southern Peru to Antofagasta, and their mummification practices reveal a close relationship with the shore. Later Atacameño communities and, under Inca rule, Aymara groups inhabited the interior; many towns remained near the coast, while oases linked inland valleys to the Altiplano. After Spanish conquest, ports carried silver from Potosí and other mining centers. Guano and saltpeter exports later drew migrants and intensified competition between Chile, Bolivia and Peru, culminating in the War of the Pacific. These routes tied an exceptionally dry coast to far-reaching markets.