While its geographical position close to the equator would correspond to a tropical climate, with dense vegetation, several factors make the Peruvian coast extremely arid desert. On the one hand, the presence of the Andes to the east prevents wind and moisture laden clouds reach the coast; secondly, the presence of the Peruvian or Humboldt Current, cold water, generates a phenomenon typical of the Peruvian coast, which prevents the presence of tropical rains, providing instead moisture accumulation by way of a dense mantle: the fog.

With no rains on the Peruvian coast, the main source of water are rivers, born in the Andes that run westward flowing into the Pacific Ocean. The rivers cut through the desert, forming valleys are real oasis. While