Above the surface, it can look like just a sunny day on Lake Michigan.
From the shores of Manitowoc, nothing out there seems to be amiss.
Below the surface, as the water goes deeper and darker, a mystery is revealed.
"A lot of interesting stories have come out of that region of Lake Michigan," Wisconsin Maritime Museum submarine curator Karen Duvalle said.
The stories involve shipwrecks, plane crashes, and UFO sightings.
"No one knows why," Duvalle said.
Its a stretch from Manitwoc, across the lake to Luddington, Michigan, down to Benton Harbor, Michigan and back to Manitowoc.
"That's the area that people believe to be the Lake Michigan triangle," Duvalle said.
Duvalle said that the legend began more than a century ago.
"There was a ship called the Thomas Hume that was built in Manitowc in 1870," Duvalle said.
The ship was a three-masted Schooner which left Chicago in 1891 and never came back.
"Thomas Hume kept going and disappeared," Duvalle said. "There was no trace of any part of the shipwreck. Usually shipwrecks will leave some timber or debris left behind, nothing, completely disappeared."
Then, 30 years later, another Schooner brought another mystery.
"There was the case of the Rosabelle," Duvalle said. "They found her floating in the lake upside down. No one reported having contact with the ship, much less a collision. The crew was missing."
Years later, a captain who went to nap was never seen again.
"The crew member went to wake him and find him and he wasn't answering, so he broke through the door, the door was locked from the inside, and the captain was missing," Duvalle said.
What connects all of these strange stories is a lack of explanation. There are many unknowns about these wrecks.
"I think it's just one of those hidden secrets of the lake that it's not really well known, but it's kind of an interesting story, interesting theories," Duvalle said.
There are theories but not answers. Many of the triangle's mysteries are still unsolved today. So next time you look across the lake, remember the legend lingering below.