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.
Wyandotte Caves
The main entrance to Wyandotte Cave is 220 feet (67 m) above the level of the Blue River. Wyandotte Cave is known for its long open passageways and large rooms. With 9.2 miles (14.806 km) of passageways on five levels it is the fifth longest cave in Indiana. Included in its formations is Monument Mountain. At 135 feet (41.148 m) tall, Monument Mountain is considered to be the world's largest underground mountain. Wyandotte Cave is also home to a great many helictites, which are considered rare. The cave is also home to the tallest stalagmite in the world, known as the Pillar of the Constitution, but this is only visible on crawling tours.