Divers have gone down to the murky depths of the lake to check out the strange underwater pyramids. And sometimes they're visible from an airplane when the water's clear.
Here's a link to an
aerial photo
of this mysterious Wisconsin attraction.
So what's the story about these weird pyramid structures?
No one is really sure.
And for most people, these weird pyramids are kind of hard to go see.
So luckily for everyone who has pyramids on their "weird and unusual things to see in America" list, nearby Aztalan State Park has a couple.
They are flat-topped pyramidal mounds believed to have been built by an ancient Native American culture.
Photo courtesy mysterious world.com
Location: Aztalan State Park is on Highway Q, near