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.
Cave diving
Hranice Abyss, or Hranická Propast, is the world's deepest known underwater cavity. It beat the previous record holder, Pozzo del Merro in Italy, by . Polish explorer Krzysztof Starnawski, who has explored the upper parts of the flooded fissure for decades, has determined the depth to be at least . As of 2017, divers have yet to reach the bottom of the cave.