River Hall lies 283 feet beneath your feet on the Historic Tour route. Usually dry, this passage fills with water when Mammoth Cave's River Styx floods into it. Most of the cave stays dry during floods; River Hall is the only toured section of the cave in the floodplain.
Poet and abolitionist Lydia Maria Child wrote of River Hall when visiting Mammoth Cave:
The River Hall descends like the slope of a mountain; the ceiling stretches away - away before you, vast and grand as the firmament at midnight.
-Letters from New-York, 1845