Footprints Discovered Underwater On The Mackinac Bridge

It's not the place people typically find themselves: under the Mackinac Bridge. Bridges are meant to be gone over, whether you're walking or driving. Considering the Mighty Mac towers 552 ft over Lake Michigan/Huron, there isn't much reason to ever be under the bridge unless you're in a boat.

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Still, some people are crazy enough to brave the waves of the Great Lakes and swim under the towers. If you are one of those people, you may find a hidden secret under the water all the way back from 1954.

Green suspension bridge over bright blue water

Mackinac Bridge's Submerged Footprints

Chris Totten recently shared a video on Facebook of him floating in the water under the Mackinac Bridge, near the North Tower. His video goes from showing the afternoon sky to what lies underwater: boot prints forever hidden. How these got here is a bigger subject: how designers figured out how to pour concrete underwater.

As it turns out, at the time of pouring, neither the workers nor the concrete was underwater. Using a combination of caissons and a structure known as a cofferdam, the builders of the Mack were able to separate the areas of water the piers were needed at, pump out the water, and work in a dry environment.

READ MORE: This Is How Many People Died Building The Mackinac Bridge

This was the situation for the workers whose footprints are now enshrined a few feet underwater when they stepped into that wet cement. According to "Building the Mighty Mac" by Linda McMaken, caissons were used on piers 18, 19, and 20, while cofferdams were used on the other 30 water piers.

There are thousands of crawlways and tunnels inside the bridge, so there's no telling how many other secrets are hidden inside the bridge.