San Pedro is one of the tallest active volcanoes in the world. It is located on the edge of the Atacama Desert

Atacama Desert

The Atacama Desert is a plateau in South America, covering a strip of land on the Pacific coast, west of the Andes mountains. It is, according to NASA, National Geographic and many other publications, the driest desert in the world...

, in Chile

Chile

Chile ,officially the Republic of Chile , is a country in South America occupying a long, narrow coastal strip between the Andes mountains to the east and the Pacific Ocean to the west. It borders Peru to the north, Bolivia to the northeast, Argentina to the east, and the Drake Passage in the far...

. San Pablo volcano is its neighbor to the east and from which is connected by a high saddle. Cerro Paniri volcano lies on the opposite side of the San Pedro River Valley. When climbing this volcano you have to wear a mask over your mouth to block out harmful toxins.