What is the name of the famous cave system located in Kentucky, USA?

Which mountain is the highest peak in North America? Which lake is the deepest in the world? What is the name of the famous prehistoric monument located in Wiltshire, England? Which island nation is home to the famous volcano Mount Yasur? What is the name of the famous delta located in Egypt? What is the name of the famous cave system located in Vietnam? Which river flows through the famous Plitvice Lakes National Park in Croatia? Which river flows through the famous Manaus city in Brazil?