How Deep is Lake Michigan?

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I’ve grown up along the shores of Michigan’s West Coast, and I’ve traveled by ferry across Lake Michigan several times.  I’ve been out on its waters on pleasure cruises and fishing expeditions. I always wondered how deep the lake is, so I decided to research it to find out. 

How deep is Lake Michigan? Lake Michigan is 925 feet (282 meters) deep at its deepest point, which is in the Chippewa Basin in the north part of the lake about 36 miles east of Forestville, Wisconsin.  The lake’s average depth is 279 feet (85 meters) deep.  Where Lake Michigan joins Lake Huron–the Straits of Mackinac, the average depth is 120 feet (40 meters).

These numbers don’t really give us a true understanding.  Read on to find out.

The Depth of Lake Michigan in Compared to Other Lakes

Compared to the other Great Lakes, Lake Michigan is second deepest, losing out to Lake Superior, which has a depth of 1,333 ft (406 m), about 44% deeper than Lake Michigan.    

But based on average depth, it is only the third deepest, losing out to Lake Superior and Lake Ontario–the latter by only a meter.  

The reason its average depth is less than Lake Ontario is that Lake Michigan consists of two large basins, with most of the lake made up from the shallower basin.  The deepest is the Chippewa basin in the north portion of the lake. The South Chippewa basin in the southern half is not as deep at about 165 meters, with a much more gradual increase in depth.  It really is like a giant bowl. You can travel 8 miles out from the Chicago shoreline, and the lake is only 65 feet deep. The high point between the two basins, which runs roughly between Milwaukee, Wisconsin and Muskegon, Michigan is called uncreatively the Mid-Lake Plateau.  The shallowest point is about 40 meters. At the low water point in the Lake’s history, this area would have been an island.

If you compare the depth of Lake Michigan to that of a couple other famous freshwater lakes–Loch Ness and Lake Champlain, Lake Michigan stacks up well.  

Loch Ness, the home of famous sea monster “Nessie”, is officially 754 feet (229.8 meters) at its deepest, although a recent unofficial survey says a previously unknown crevice at the bottom is 889 feet (271 meters) is the deepest point.  Despite that, the average depth of Loch Ness is over 50% deeper than Lake Michigan at 433 feet (132 meters).  

By contrast, Lake Champlain, home to the alleged sea monster “Champ”, is a much shallower lake.  It has an average depth of 64 feet, with the deepest point being about 400 feet deep.  

Lake Michigan, Loch Ness, and Lake Champlain were all formed about the same time–after the last Ice Age 10,000 years ago.  All three are fresh water lakes.  

There have been multiple sightings of a lake monster on Loch Ness and Lake Champlain.  With Lake Michigan being fresh water, forming at the same time of these other lakes, and a greater depth to boot, could Lake Michigan house a lake monster of its own?  Hmmm. You decide.

The Depth of Lake Michigan in Real Terms

But maybe to get a real sense of the depth of Lake Michigan, we need to compare it to above-ground features that people are familiar with, like skyscrapers.  In comparison to this, Lake Michigan won’t stack up well. After all, 925 feet is roughly equivalent to a 92 story building, and there are many, many buildings taller than that nowadays.  

The Empire State building in New York City is about 1,250 feet (380 meters) tall.  If you submerged it in the deepest point in Lake Michigan, 32 stories would be above water level. (A story is about 10 feet. The Empire State building actually has 102 floors in it, which is sometimes equated with stories. There is extra height in non-habitable space.)

The Sears Tower, known these days as the Willis Tower, in Chicago on the shore of Lake Michigan is 1450 feet tall.  This building is the second tallest in the Western Hemisphere. If this building were submerged in Lake Michigan’s deepest point, more than a third of the building would be out of the water!!!  Over 100 ft of the tip-top of this building would even be out of water if it were submerged in Lake Superior, the 4th deepest lake in the country.

What Lives at the Bottom of Lake Michigan?

Still, 925 feet is deep by many standards.  At this depth, the water pressure would be crushing.  Recreational divers can only dive to a maximum of 120 feet (30 meters).  But unlike oceans, there isn’t much living at this depth.  

Brendon Baillod is the president of the Wisconsin Underwater Archaeology Association.  He has explored shipwrecks on the bottom of Lake Michigan. “Because the (great) lakes don’t have any of the marine boring worms that the ocean has, there’s not much life on the bottom of the lake — it preserves wood tremendously well,” he says.

The deepest fish species in Lake Michigan appear to be Lake Whitefish, which can be found at depths of over 200 feet.  

Related Questions

What is the water temperature at Lake Michigan’s deepest point?   At 925 feet, the water temperature is a constant 39 degrees F, with little variation throughout the year, even in winter. 

Does a sea serpent live in Lake Michigan?:  In July 2019, Tim Wenzel posted video footage from a live webcam during a summer squall.  It purportedly shows a long serpent-like shape getting washed up on and over the pier. It appears to dive back into the water at the end of the footage.  Watch the video footage here: