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.
Vorontsovka Caves
The Vorontsovskaya Cave System (Воронцовская система пещер) is a long chain of caves in the Khosta and Adler districts of Sochi, Russia. It is part of a range of Mesozoic limestones that runs parallel to the Black Sea coast for 400 km. and contains the Voronya Cave, the world's deepest cave.