General Caving

National Speleological Society (NSS)
Living on Karst - A reference guide for landowners in limestone regions.
National Cave Rescue Commission (NCRC)
NSS Geo2 Long & Deep Cave Lists
SPELEO Link Page
USGS Exploring Caves

Local Caving Organizations

Northeastern Cave Conservancy
NSS Grotto Information for Pennsylvania
Bald Eagle Grotto
Cave Hill Grotto
District of Columbia Grotto
Franklin County Grotto
Huntingdon County Cave Hunters
Loyalhanna Grotto
Mid-Appalachian Region (MAR)
Mid-Atlantic Karst Conservancy (MAKC)
Nittany Grotto
Northeast Cave Conservancy
Northern New Jersey Grotto
Pennsylvania Cave Conservancy (PCC)
Philadelphia Grotto
Pittsburgh Grotto

Surveying & Mapping

Cave Surveying
Aerial Photographs and Topo Maps
NSS Survey and Cartography Section
WinKarst Cave Mapping Software - The bottom of this page has pointers to other useful mapping software.
Compass Cave Survey Software

PA Resources

Pennsylvania Bat Specifics - Descriptions & photos of bats that live in PA.
Pennsylvania Cave Conservancy
Pennsylvania Topographic & Geologic Survey

Other Links

NEARCTICA - The Natural History of North America including Education, Family subjects, Natural History, Conservation, Environment, Ecology, Evolution, Geology, Paleontology, Commerce, Organizations and Systematics.
OTR - Old Timers Reunion