Abismo Guy Collet
The Abismo Guy Collet (SP-090) is the deepest cave in South America, and the deepest in the world that is formed in quartzite. Located in a tepui in northern Brazil near the border with Venezuela, this cave was first explored by cavers in 2006 to a depth of 671 meters.
Stephen Alvarez
On another National Geographic assignment Alvarez photographed the deepest cave in the world, Voronya Cave, located 2000 meters beneath the Caucasus Mountains in the breakaway Russian republic of Abkhazia.