The lack of rain on the Peruvian coast is chiefly due to two important circumstances, which explain why neither the winds from the Pacific nor those from the Atlantic discharge any moisture on this sandy soil. The prevailing winds from the Pacific blow from the southeast and carry very little moisture, owing to their courses being parallel with that of the Humboldt current,—a submarine stream from the antarctic, which follows the line of the Peruvian coast throughout its entire length and has a temperature seven degrees colder than the ocean; it is a hundred and fifty miles wide, with a velocity of about a mile an hour. Besides the southeast wind, a west wind blows across the Pacific, bringing plenty of rainclouds; but it is checked by the stronger southeast current as it approaches the coast, and its benefits are lost. The trade winds that cross the Amazon plain from the Atlantic discharge a great amount of rain in their course, but when they reach the high altitudes of the Andean range, their vapor is condensed and falls in the form of snow, no moisture remaining with which to water the narrow strip that lies between the Cordilleras and the Pacific. The sea breeze, known as the _virazón_, is strongest along the southern part of the coast, where, during the winter months, it sometimes causes inconvenience in the various harbors, on account of the heavy surf it creates. As a rule, the Peruvian coast presents few difficulties to navigation. It is seldom visited by storms, and there are no rocks, reefs, or shoals, to give the mariner anxiety. A remarkable feature of the ocean in this region is the appearance, during the winter season, of a current which is supposed to be a prolongation of the equatorial stream, and which flows in an opposite direction to the Humboldt current; it is known as the _niño_. [Illustration: SCENE ON THE TUMBES RIVER.]