
Go there: Mammoth Cave National Park in Mammoth Cave, Ky., has 14 miles of cave trails, 31 miles of river and 85 miles of hiking trails. There’s no fee to enter the park, but fees are charged for Mammoth Cave tours, which can last from 30 minutes to more than six hours. Carlsbad Caverns National Park charges an entrance fee for self-guided tours of the 8.2-acre Big Room area of the cave (adults, .. more …















