An explorer of the Mammoth Cave system in Kentucky who died 100 years ago is credited with the creation of the national park. WKYU's Michael Collins reports. This segment airs on February 19, 2025.

Prior to this discovery, the largest underground thermal lake title belonged to a site in Hungary, below Turkish baths in the city of Budapest, Reuters reported in 2008. That lake is 282 feet long, 89 ...