Dozens of Massive Craters Found in Lake Michigan – But Asteroids Aren’t to Blame

A few years ago, scientists discovered mysterious circles at the bottom of Lake Michigan while mapping the lakebed within the Wisconsin Shipwreck Coast National Marine Sanctuary in 2022. Now, two years later, they believe they have uncovered the reason behind these unusual formations, concluding that the circles are actually giant holes.

Russ Green, a maritime archaeologist and superintendent of the sanctuary, participated in the expedition and shared with *Live Science* that the circles initially appeared as natural features. The circles resembled depressions on the lakebed, but there was no clear confirmation of their origin.

Brendon Baillod, a local shipwreck hunter, also observed these circles and suspected they were craters, ranging from 20 to 40 feet (6 to 12 meters) deep. He commented to *Live Science*, “There were dozens of them in our search grid.”

In an effort to investigate further, researchers contacted scientists from the National Oceanic and Atmospheric Administration’s (NOAA) Great Lakes Environmental Research Laboratory (GLERL).

The circles were then examined through a joint mission, with a remotely operated vehicle sent down to study the formations. The team confirmed that these were large, naturally occurring craters, and around 40 of them were identified. However, according to GLERL researcher Steve Ruberg, there may be even more.

Similar depressions had previously been discovered at the bottom of Lake Huron, which borders Michigan and Canada, and these were found to be sinkholes. Sinkholes typically form when groundwater dissolves underlying bedrock, causing the surface to collapse. Given that Lake Michigan partly sits on limestone, a rock type susceptible to dissolution, Ruberg speculated that these craters could also be sinkholes.

However, not all experts agree with this explanation. Baillod suggested that the formations might more accurately be described as craters formed by water upwelling from below or by the release of trapped hydrocarbons.

So far, no evidence of water escaping from the holes has been detected, which suggests there could be groundwater circulating beneath the lakebed. Nonetheless, Ruberg remains hopeful that further research may reveal some signs of this in the future.

Green emphasized that additional studies will be necessary to fully understand what these craters are and their potential impact on Lake Michigan.