National Cave and Karst Research Institute
Conceived by cavers Jim Goodbar, Ronal Kerbo, and Jerry Trout in the early 1980s, the National Cave and Karst Research Institute (NCKRI) was created by the US Congress as the country’s authority on caves and karst. Twenty-five percent of the USA is karst and related pseudokarst terrain, which occurs in all 50 states. NCKRI works across the country to study and better manage these resources, which includes much of the nation’s water supply, and to minimize problems from sinkhole collapse and other challenges.Visit the National Cave and Karst Research Institute
Longest cave system
Mammoth Cave, in Mammoth Cave National Park, Kentucky, USA, is a network of connected limestone caves of which around 663 km (412 mi) have been explored to date. It has taken some 25 million years to form owing to the weathering action of the Green River and its tributaries. Mammoth Cave is home to around 200 indigenous species, most of which are invertebrates.