Grotto (National Speleological Society)
A Grotto is an internal organization of the National Speleological Society (NSS). They generally function as the local NSS chapter/club. Many Grottos however, operate in areas outside of their local area, with many operating in several states. Most Grottos also participate in Regions which are loose associations of Grottos. Regions are also an internal organization of the National Speleological Society.
Read more about Grotto (National Speleological Society): Organization, History, Grottos of The NSS