Lake Science
The Biggest, Deepest and Clearest Lakes in Minnesota
Minnesota's largest lakes by acreage, the deepest natural lake and the deeper mine pit that beats it, and where the clearest water is, with DNR figures.
Updated
The largest lake entirely inside Minnesota is Red Lake at 288,800 acres, the deepest natural lake is Saganaga at 280 feet, and the clearest water in state survey data sits in flooded iron mine pits near Crosby and on the Iron Range. Every one of those answers comes with an asterisk, because Minnesota shares its two biggest lakes with neighbors and its deepest inland water is not a natural lake at all. The figures below come from the Minnesota DNR lakes, rivers and wetlands facts page and from individual lake surveys in DNR LakeFinder, checked in October 2026.
The largest lakes
Entirely inside Minnesota
The DNR's ten largest lakes that sit wholly within the state:
| Rank | Lake | Area (acres) | Where |
|---|---|---|---|
| 1 | Red Lake (Upper and Lower) | 288,800 | Beltrami County |
| 2 | Mille Lacs | 132,516 | Mille Lacs, Aitkin, Crow Wing counties |
| 3 | Leech | 111,527 | Cass County |
| 4 | Winnibigoshish | 58,544 | Cass and Itasca counties |
| 5 | Vermilion | 40,557 | St. Louis County |
| 6 | Kabetogama | 25,760 | St. Louis County |
| 7 | Mud Lake | 23,700 | Marshall County |
| 8 | Cass | 15,596 | Beltrami and Cass counties |
| 9 | Minnetonka | 14,004 | Hennepin County |
| 10 | Otter Tail | 13,725 | Otter Tail County |
A few notes a local would add. Red Lake is two basins joined by a narrows, and most of it lies within the Red Lake Nation; the public fishery most people know is the eastern part of Upper Red near Waskish. Mud Lake in Marshall County is a shallow wetland basin inside Agassiz National Wildlife Refuge (the refuge was originally named for it), not a boating lake. Kabetogama is the big lake of Voyageurs National Park that does not touch Canada.
Acreage also depends on who measured and when. LakeFinder's survey pages list slightly different numbers for several of these lakes (Leech at about 103,400 acres, Mille Lacs at about 128,300), because survey boundaries and water levels differ. Treat any acreage as good to within a few percent.
Border waters
| Lake | Total area (acres) | In Minnesota (acres) | Shared with |
|---|---|---|---|
| Lake Superior | 20,364,800 | 962,700 | Wisconsin, Michigan, Ontario |
| Lake of the Woods | 950,400 | 307,010 | Ontario, Manitoba |
Even counting only the Minnesota portion, Superior is the largest body of water in the state, and Minnesota's slice of Lake of the Woods is bigger than Red Lake. Rainy Lake is another large border water; LakeFinder lists it at roughly 210,000 acres including the Ontario side. On the southeast edge, Lake Pepin covers 29,295 acres of the Mississippi River between Minnesota and Wisconsin, and the DNR describes it as the state's sixth-largest lake.
Longest shoreline
The DNR gives Lake Vermilion the longest shoreline of any Minnesota lake at 290 miles, thanks to hundreds of islands and long, crooked bays. That is why Vermilion fishes like a dozen different lakes and why a map matters there more than almost anywhere.
The deepest lakes
Depth has three different answers depending on what you count.
- Deepest water touching Minnesota: Lake Superior. The DNR lists its maximum depth at 1,290 feet; other agencies publish slightly different soundings, all around 1,300 feet.
- Deepest inland lake: the connected Mahnomen, Alstead and Arco mine pit near Crosby in Crow Wing County, 525 feet. It is part of Cuyuna Country State Recreation Area.
- Deepest natural inland lake: Lake Saganaga in Cook County, 280 feet. It straddles the Ontario border at the end of the Gunflint Trail.
Other deep natural lakes on the DNR list include Loon Lake in Cook County (215 feet), Lower LaSalle in Hubbard County (213 feet), Ten Mile in Cass County (208 feet) and Rainy (161 feet). Among the famous big lakes, depth is modest: Leech reaches 150 feet, Minnetonka 113, Vermilion 76, Winnibigoshish 70, Mille Lacs just 42 and Upper Red only 18.
Mine pits crowd the top of any depth ranking. LakeFinder lists the Sabin pit (Embarrass Mine) near Aurora at 465 feet, the Gilbert pit that locals call Lake Ore-be-gone at 443 feet and Portsmouth at Cuyuna at 395 feet. Portsmouth is often quoted at 450 feet or more in older sources; the DNR's current survey figure is 395. More on those in the mine pit lakes guide.
Deep does not mean big. Lower LaSalle is under 250 acres. It is a narrow trench, which is why it outranks lakes fifty times its size.
The clearest lakes
Clarity is measured with a Secchi disk, a black-and-white plate lowered until it disappears. The depth where it vanishes is the reading. Volunteers and agency crews take these readings on thousands of lakes for the MPCA and DNR, and the University of Minnesota's LakeBrowser estimates clarity for more than 10,000 lakes from satellite images.
No agency crowns a single clearest lake, and a wet year or an algae bloom can move a lake's number by several feet. With that caveat, here are average clarity figures from LakeFinder for lakes we checked:
| Lake | County | Average clarity (feet) | Type |
|---|---|---|---|
| Sabin (Embarrass Mine) | St. Louis | 38.7 | Mine pit |
| Huntington Mine | Crow Wing | 38.5 | Mine pit |
| Judson Mine Pit | St. Louis | 33.0 | Mine pit |
| Mahnomen, Alstead and Arco | Crow Wing | 32.3 | Mine pit |
| Caribou (near Marcell) | Itasca | 30.8 | Natural |
| Portsmouth Mine | Crow Wing | 30.5 | Mine pit |
| Christmas | Hennepin | 26.0 | Natural |
| Wabana | Itasca | 18.6 | Natural |
| Burntside | St. Louis | 18.1 | Natural |
| Ten Mile | Cass | 17.4 | Natural |
This is a sample, not a statewide ranking. It does show the pattern. Mine pits win because they are deep, steep and starved of nutrients. Natural lakes with exceptional clarity tend to be deep, small-watershed lakes in forested country: the Marcell and Grand Rapids area of Itasca County, the Ely area, and the deep lakes around Hackensack and Walker. Christmas Lake, next to Lake Minnetonka, is the proof that a metro lake can be very clear too.
At the other end, shallow prairie lakes in farm country are naturally murky. Lake Shetek in Murray County averages about one foot of clarity. That is not a failure of the lake so much as what a 10-foot-deep, wind-stirred basin in rich soil looks like.
One caution: a sudden jump in clarity is not always good news. Zebra mussels filter the water and can make an infested lake look cleaner while reshaping its food web. See the site's list of the clearest lakes for more, and the invasive species guide before you move a boat between waters.
Bottom line
- Biggest inside the state: Red Lake, then Mille Lacs, then Leech. Biggest overall: Superior, then Lake of the Woods.
- Deepest natural lake: Saganaga at 280 feet. Deepest inland water: a 525-foot mine pit near Crosby.
- Clearest: mine pits first, then deep forest lakes in the north. Check a specific lake's survey page in LakeFinder, because the published numbers get revised.