Detail of cave pearl formations in Lechuguilla Cave, New Mexico. [{"term_id":"23","name":"episode 4","slug":"episode-4","term_group":"0","term_taxonomy_id":"26","taxonomy":"media-tags","description":"","parent":"0","count":"17"}]114
The Cave of Swallows had the largest known cave shaft in the world.[{"term_id":"68","name":"Cave of Swallows","slug":"cave-of-swallows","term_group":"0","term_taxonomy_id":"79","taxonomy":"media-tags","description":"","parent":"0","count":"4"},{"term_id":"23","name":"episode 4","slug":"episode-4","term_group":"0","term_taxonomy_id":"26","taxonomy":"media-tags","description":"","parent":"0","count":"17"}]392
The Cave of Swallows is located in the Municipality of Aquismón, San Luis Potosí, Mexico.[{"term_id":"68","name":"Cave of Swallows","slug":"cave-of-swallows","term_group":"0","term_taxonomy_id":"79","taxonomy":"media-tags","description":"","parent":"0","count":"4"},{"term_id":"23","name":"episode 4","slug":"episode-4","term_group":"0","term_taxonomy_id":"26","taxonomy":"media-tags","description":"","parent":"0","count":"17"}]391
A base jumper falls into the Cave of Swallows in Mexico.[{"term_id":"68","name":"Cave of Swallows","slug":"cave-of-swallows","term_group":"0","term_taxonomy_id":"79","taxonomy":"media-tags","description":"","parent":"0","count":"4"},{"term_id":"23","name":"episode 4","slug":"episode-4","term_group":"0","term_taxonomy_id":"26","taxonomy":"media-tags","description":"","parent":"0","count":"17"}]390
Cockroaches gather in the Gomantong Cave in Borneo.[{"term_id":"69","name":"cockroaches","slug":"cockroaches","term_group":"0","term_taxonomy_id":"80","taxonomy":"media-tags","description":"","parent":"0","count":"1"},{"term_id":"23","name":"episode 4","slug":"episode-4","term_group":"0","term_taxonomy_id":"26","taxonomy":"media-tags","description":"","parent":"0","count":"17"}]389
A view of the Cave of Swallows in Mexico.[{"term_id":"68","name":"Cave of Swallows","slug":"cave-of-swallows","term_group":"0","term_taxonomy_id":"79","taxonomy":"media-tags","description":"","parent":"0","count":"4"},{"term_id":"23","name":"episode 4","slug":"episode-4","term_group":"0","term_taxonomy_id":"26","taxonomy":"media-tags","description":"","parent":"0","count":"17"}]388
The texas blind salamander is a rare amphibian.[{"term_id":"23","name":"episode 4","slug":"episode-4","term_group":"0","term_taxonomy_id":"26","taxonomy":"media-tags","description":"","parent":"0","count":"17"},{"term_id":"22","name":"salamander","slug":"salamander","term_group":"0","term_taxonomy_id":"24","taxonomy":"media-tags","description":"","parent":"0","count":"3"}]387
Caved swiftlets, known for their narrow wings for fast flight, nest in both tropical and subtropical regions. [{"term_id":"23","name":"episode 4","slug":"episode-4","term_group":"0","term_taxonomy_id":"26","taxonomy":"media-tags","description":"","parent":"0","count":"17"},{"term_id":"67","name":"swiftlet","slug":"swiftlet","term_group":"0","term_taxonomy_id":"78","taxonomy":"media-tags","description":"","parent":"0","count":"1"}]386
Base jumper at Cave of Swallows, Mexico. [{"term_id":"23","name":"episode 4","slug":"episode-4","term_group":"0","term_taxonomy_id":"26","taxonomy":"media-tags","description":"","parent":"0","count":"17"}]267
Base jumper at Cave of Swallows, Mexico.[{"term_id":"23","name":"episode 4","slug":"episode-4","term_group":"0","term_taxonomy_id":"26","taxonomy":"media-tags","description":"","parent":"0","count":"17"}]217
Blind cave salamander in Texas.[{"term_id":"23","name":"episode 4","slug":"episode-4","term_group":"0","term_taxonomy_id":"26","taxonomy":"media-tags","description":"","parent":"0","count":"17"}]134
An aerieal view of Ha Long Bay, Vietnam.[{"term_id":"23","name":"episode 4","slug":"episode-4","term_group":"0","term_taxonomy_id":"26","taxonomy":"media-tags","description":"","parent":"0","count":"17"}]133
Lechuguilla Cave in Carlsbad Caverns National Park, New Mexico. [{"term_id":"23","name":"episode 4","slug":"episode-4","term_group":"0","term_taxonomy_id":"26","taxonomy":"media-tags","description":"","parent":"0","count":"17"}]132
Base jumper at Cave of Swallows, Mexico.[{"term_id":"23","name":"episode 4","slug":"episode-4","term_group":"0","term_taxonomy_id":"26","taxonomy":"media-tags","description":"","parent":"0","count":"17"}]119
Base jumper at Cave of Swallows, Mexico.[{"term_id":"23","name":"episode 4","slug":"episode-4","term_group":"0","term_taxonomy_id":"26","taxonomy":"media-tags","description":"","parent":"0","count":"17"}]118
Stalactites in a cave in Wales, UK.[{"term_id":"23","name":"episode 4","slug":"episode-4","term_group":"0","term_taxonomy_id":"26","taxonomy":"media-tags","description":"","parent":"0","count":"17"}]117
A group of swiftlets spotted nesting in a cave.[{"term_id":"23","name":"episode 4","slug":"episode-4","term_group":"0","term_taxonomy_id":"26","taxonomy":"media-tags","description":"","parent":"0","count":"17"},{"term_id":"70","name":"swiftlets","slug":"swiftlets","term_group":"0","term_taxonomy_id":"81","taxonomy":"media-tags","description":"","parent":"0","count":"1"}]393
Caves