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.
Xe Bang Fai River
Xe Bang Fai River Cave, also known as Khoun Xe Cave (Tham in Laotian is "Cave"), is an immense river cave located in a remote corner of Khammouane Province. It is believed to be one of the largest river cave in the world with enormous passages some 120 meters tall and 200 meters wide, and subterranean channel 7 km long.