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.
Cades Cove
The fracturing and weathering of the limestone and sandstone in Cades Cove has led to the formation of several caves in the vicinity, the two largest of which are Gregory's Cave and Bull Cave. Bull Cave, at 924 feet (281 m), is the deepest cave in Tennessee. Trilobite and brachiopod fossils have been found in Gregory's Cave.