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.
Ali-Sadr Cave
The Ali Sadr Cave (Persian: غار علی صدر) originally called Ali Saadr or Ali Saard (meaning cold) is the world's largest water cave which attracts thousands of visitors every year. It is located in Ali Sadr Kabudarahang County about 100 kilometers north of Hamadan, western Iran (more accurately at 48°18'E 35°18'N). Because of the cave's proximity to large cities such as Hamadan, it is a highly recommended destination for tourists from all corners of the world. Tours of the cave are available by pedalos.
Alisadr is the world's largest water cave, where you sit in a boat and watch the view.
This cave is located at 48°18'E 35°18'N, in the southern part of Ali Sadr village. The cave is entered at the side of a hill called Sari Ghiyeh which also includes two other caves called Sarab and Soubashi, each 7 and 11 kilometers from Ali Sadr Cave. Apparently, the water in Ali Sadr cave stems from a spring in Sarab.