Cave of Crystals, Mexico(01 of29)
Open Image Modal (credit:NAICA)
Cueva de los Verdes, Spain(02 of29)
Open Image Modal (credit:Flickr:Christ0ff)
Postojna Caves, Slovenia(03 of29)
Open Image Modal (credit:Flickr:hanspoldoja)
Waitomo Glowworm Cave, New Zealand(04 of29)
Open Image Modal (credit:Flickr:m0bile)
Eisriesenwelt Ice Caves, Austria(05 of29)
Open Image Modal (credit:Eisriesenwelt Official Website)
Lehman Caves, Nevada(06 of29)
Open Image Modal (credit:Flickr:Alaskan Dude)
Jameos del Agua, Canary Islands(07 of29)
Open Image Modal (credit:Flickr:guillenperez)
Reed Flute Cave, China(08 of29)
Open Image Modal (credit:Flickr:clip works)
Fantasy Cave, Bermuda(09 of29)
Open Image Modal (credit:Flickr:walknboston)
Batu Caves, Malaysia(10 of29)
Open Image Modal (credit:Flickr:Christian Haugen)
Nigardsbreen Ice Cave, Norway(11 of29)
Open Image Modal (credit:Flickr:Guttorm Flatab�)
Alisadr Cave, Iran(12 of29)
Open Image Modal (credit:Flickr:Hamed Saber)
Onondaga Cave, Missouri(13 of29)
Open Image Modal (credit:Flickr:MGSwarbs)
Halong Bay Caves, Vietnam(14 of29)
Open Image Modal (credit:Flickr:Dave_B_)
Kverkfjöll Ice Caves, Iceland (15 of29)
Open Image Modal (credit:Flickr:ezioman)
Deer Cave, Malaysia(16 of29)
Open Image Modal (credit:Flickr:NeilsPhotography)
Crystal Ice Cave, Lava Beds National Monument, California(17 of29)
Open Image Modal (credit:Flickr:ex_magician)
Cuevas del Drach, Spain(18 of29)
Open Image Modal (credit:Flickr:no)
Lechuguilla Cave, Carlsbad Caverns, New Mexico(19 of29)
Open Image Modal (credit:Dave Bunnell)
Padirac Cave, France(20 of29)
Open Image Modal (credit:Flickr:jurvetson)
Jeita Grotto, Lebanon(21 of29)
Open Image Modal (credit:Jeita Groto Official Website)
Grotta Azzurra, Capri(22 of29)
Open Image Modal (credit:Flickr:dr_tr)
Harrison's Cave, Barbados(23 of29)
Open Image Modal (credit:Flickr:randystoreyphotography)
Phong Nha Caves, Vietnam(24 of29)
Open Image Modal (credit:Genghiskhanviet)
Luray Caverns, Virginia(25 of29)
Open Image Modal (credit:Flickr:InnocentEyez)
Marengo Cave, Indiana(26 of29)
Open Image Modal (credit:Flickr:daveynin)
Mammoth Caves, Kentucky(27 of29)
Open Image Modal (credit:Flickr:daveynin)
Lost Sea - Sweetwater, Tennessee(28 of29)
Open Image ModalPatrickAaron:
America\'s Largest Underground Lake
Stephen's Gap Cave, Scottsboro, AL, USA(29 of29)
Open Image Modalspartancaver:
Setphen\'s Gap Cave, enlarge to see the person rappelling into the cave.