The Great Lakes are massive and continue to hold many mysteries. One group of researchers recently found something unexpected on the floor of Lake Michigan and so far, scientists can’t figure out why they are there.

The initial discovery took place about two years ago when the Wisconsin Shipwreck Coast Maritime Sanctuary (WSCMS) surveyed the area where at least 36 different shipwrecks have occurred in the past.

The goal was to locate these shipwrecks for further study, but they also found these unexplained holes.

The National Oceanic and Atmospheric Administration’s (NOAA) Great Lakes Environmental Research Laboratory provided a robotic submarine to analyze the holes closer, but they still can’t say exactly what caused them.

In a statement given to LiveScience, maritime archaeologist Russ Green said:

“Any kind of new discovery in the Great Lakes is exciting. But these features really stand out — they are in deeper water… and weren’t known before, as far as we can tell.”

A shipwreck enthusiast, Brendon Baillod, also looked at these holes and said that based on his measurements, they are 20-40 feet deep. He went on:

“There were dozens of them in our search grid. Most were 500 to 1,000 feet in diameter and of irregular shapes.”

Oddly, the holes are almost perfect circles, and there are 40 of them. Having this many nearly perfect circles hundreds of feet below the surface of Lake Michigan is unexpected, to say the least.

Green went on to say:

“We’ll be exploring them for years to come.”

It makes you wonder what caused these mysterious holes.

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