Marengo Cave U.S. National Landmark offers several tours of varying lengths and skill levels. As an example, one of first stops on the Crystal Palace tour is an immense cave where viewers look down into what appears a bottom chamber until realizing that instead they’re peering into Mirror Lake — a vast, still expanse of water that reflects the stalactites above perfectly.
Another stopping point is the Crystal Palace Room, where a flashing light show accompanies music, in a grand underground theater with stone seats and a stage. The colored lights illuminated the various stalactites and other geological wonders in what is the ultimate light show. Then there’s the 70-minute Dripstone Trail Tour which goes deeper into the cave.
For the real adventuresome, there’s the down and dirty Crawl–which is exactly like what it sounds