Indian Echo Caverns is a limestone cave system near Hershey, opened to visitors on guided tours through a series of cool chambers, narrow passages and dripstone formations. It makes a useful contrast to the chocolate-and-theme-park side of Hershey, especially on a hot or rainy day.
The cave is commercial but still geologically interesting, with the steady underground temperature and echoing rooms giving a clear sense of central Pennsylvania's karst landscape. It is best treated as a short excursion rather than a destination in itself; families will get the most out of it, but geology-minded travellers will find enough texture to justify the trip.