Lake Michigan's maximum depth is 923 feet (281 m); its average depth is 279 feet (85 m). It is the second-deepest Great Lake after Lake Superior, covering 22,404 square miles with two distinct underwater basins separated by a mid-lake plateau.
Need official navigation charts? NOAA publishes free electronic and printable depth charts for all of Lake Michigan. Browse NOAA's chart catalog →
| Measurement | Depth / Size |
|---|---|
| Maximum depth | 923 ft (281 m), Chippewa Basin |
| Average depth | 279 ft (85 m) |
| Surface area | 22,404 sq mi |
| Length / width | 307 mi / 118 mi |
| Water volume | 1,180 cubic miles |
| Shoreline | 1,640 mi |
The northern half holds the lake's deepest water. The 923-foot maximum sits in the Chippewa Basin, roughly between Charlevoix, MI and Wisconsin's Door Peninsula. Depths of 500-900 feet are common more than 10 miles offshore. Nearshore, the bottom drops fast along the Michigan side near Traverse Bay and more gradually along Wisconsin's Door County.
A broad underwater ridge crosses the lake between Milwaukee, WI and Muskegon, MI, rising to about 300-400 feet below the surface. This structure concentrates baitfish and is a well-known summer target for salmon trollers running offshore.
The southern basin bottoms out around 500-575 feet, with a much more gradual slope. Off Chicago and Northwest Indiana the bottom falls away slowly: you can be 5 miles out in less than 100 feet of water. This wide shelf is why perch and spring coho fishing is so accessible from the southern ports.
Green Bay is the lake's large shallow arm: mostly 50-120 feet, with weedy flats under 30 feet at the south end near the Fox River mouth. It fishes more like a huge inland lake, famous for walleye and smallmouth.
Depth is the single most useful variable for finding fish in Lake Michigan because species stack by temperature band:
| Depth zone | What you'll find |
|---|---|
| 0-30 ft (nearshore) | Yellow perch, smallmouth bass, spring coho and browns when water is cold |
| 30-100 ft | Perch schools on structure; spring and fall king salmon staging near river mouths |
| 100-250 ft | Summer salmon and steelhead over the thermocline; lake trout near bottom on humps |
| 250 ft+ | Offshore summer kings and steelhead suspended over deep water; lake trout on deep reefs |
In summer, the thermocline typically sets up 40-90 feet down. Trollers target salmon just above it regardless of how deep the bottom is, which is why fish are caught suspended over 500+ feet of water.
We track hundreds of Lake Michigan access points, ramps, and piers with species info for each. Start here: