The Virtual Cave
A wide-ranging introduction to the geology of caves. Organised by geological feature with pictures and clickable virtual maps.
NSS discussion forum for US cavers including sections for cave diving, news, conservation, equipment, photography, rescue and surveying.
U.S. Cavers Forum
Discussion forums including caving, the NSS, the study of speleology, cave conservation and management, bats and gear.
World Cave Database
A list of long and deep caves from all around the world. Listed by depth, length and country.