Updated August 2026

Deepest Lakes by Maximum Depth

The 50 deepest lakes ranked by maximum depth in feet, from DNR bathymetric surveys. Deeper lakes tend to hold better water quality — thermal stratification keeps bottom nutrients from mixing up to the sunlit surface where they would feed algae. Depth data currently covers Minnesota and Wisconsin; water-quality readings and clarity for every state we cover are on each state page.

The deepest lake on the index is Gilbert Pit Lake in St. Louis County, MN, at 443 ft. The deepest waters in the region are split between natural Boundary Waters and Northwoods lakes and a handful of flooded iron-ore mine pits, which plunge to extreme depths in a small footprint.

The deepest lake in Minnesota is Gilbert Pit Lake in St. Louis County, at 443 ft. The deepest lake in Wisconsin is Wazee Lake in Jackson County, at 350 ft.

Depth figures come from state DNR lake-survey morphology; nutrient, algae and Secchi clarity readings come from EPA National Aquatic Resource Surveys and state monitoring programs.

Top 3 Deepest Lakes

Gilbert Pit Lake

St. Louis County, MN

Max depth 443 ft. Clarity 11.5 ft.

St James Pit Lake

St. Louis County, MN

Max depth 381 ft. Clarity 47.6 ft.

Priest Lake

Bonner County, ID

Max depth 369 ft.

Rank	Lake	County	State	Max Depth	Area	Clarity
1	Gilbert Pit Lake	St. Louis	MN	443 ft	243 acres	11.5 ft
2	St James Pit Lake	St. Louis	MN	381 ft	124 acres	47.6 ft
3	Priest Lake	Bonner	ID	369 ft	23,426 acres	-
4	Wazee Lake	Jackson	WI	350 ft	146 acres	30 ft
5	Watauga Lake	Carter	TN	265 ft	6,353 acres	-
6	Iron Chief Complex Lake	St. Louis	MN	262.1 ft	207 acres	24.5 ft
7	Torch Lake	Antrim	MI	250 ft	18,714 acres	30 ft
8	Green Lake	Green Lake	WI	236 ft	7,920 acres	13.5 ft
9	Bull Run Lake	Clackamas	OR	230 ft	444 acres	-
10	Major Lake	Halifax	NS	213.3 ft	848 acres	13.9 ft
11	Lasalle Lake	Hubbard	MN	213 ft	238 acres	6.9 ft
12	Watap Lake	Cook	MN	210 ft	1,993 acres	9 ft
13	Sagamore Mine Lake	Crow Wing	MN	210 ft	119 acres	23.8 ft
14	Gabimichigami Lake	Cook	MN	209 ft	1,186 acres	11.5 ft
15	Ten Mile Lake	Cass	MN	208 ft	5,080 acres	20.5 ft
16	Loon Lake	Cook	MN	202 ft	1,095 acres	17.4 ft
17	Gunflint Lake	Cook	MN	200 ft	4,009 acres	16.5 ft
18	Strup Lake	Lake	MN	195 ft	1,689 acres	10 ft
19	Lake Arrowhead	Cherokee	GA	186 ft	436 acres	-
20	Sand Point Lake	St. Louis	MN	184 ft	8,527 acres	6.6 ft
21	Larson Lake	Itasca	MN	177 ft	208 acres	21 ft
22	Crystal Lake	Benzie	MI	175 ft	9,865 acres	32 ft
23	Lochaber Lake	Antigonish	NS	171.9 ft	759 acres	13.1 ft
24	Lac la Croix Lake	St. Louis	MN	168 ft	29,597 acres	8 ft
25	Charlotte Lake	Halifax	NS	168 ft	-	14.8 ft
26	Paces Lake	Halifax	NS	167.3 ft	748 acres	20.3 ft
27	Crooked Lake	Lake	MN	165 ft	10,360 acres	9 ft
28	Black Lake	Cumberland	NS	165 ft	117 acres	17.2 ft
29	Caribou Lake	Lunenburg	NS	164 ft	677 acres	29.7 ft
30	Carlos Lake	Douglas	MN	163 ft	2,605 acres	18 ft
31	Rainy Lake	Koochiching	MN	161 ft	210,200 acres	7.5 ft
32	Trout Lake	Itasca	MN	157 ft	1,743 acres	18 ft
33	Caribou Lake	Itasca	MN	152 ft	247 acres	31 ft
34	Thumb Lake	Charlevoix	MI	152 ft	508 acres	17 ft
35	Little Saganaga Lake	Cook	MN	150 ft	1,627 acres	7 ft
36	Snowbank Lake	Lake	MN	150 ft	4,655 acres	15.1 ft
37	Steamboat Bay Lake	Cass	MN	150 ft	103,444 acres	9.8 ft
38	Elk Lake	Antrim	MI	150 ft	-	14.5 ft
39	Elk Lake	Grand Traverse	MI	150 ft	8,201 acres	-
40	Shubenacadie Grand Lake	Halifax	NS	147.6 ft	-	20.7 ft
41	Six Lake	Otter Tail	MN	140 ft	197 acres	21 ft
42	Elmo Lake	Washington	MN	140 ft	257 acres	11.1 ft
43	South Lake	Cook	MN	140 ft	1,145 acres	26 ft
44	Miner'S Pit West Lake	St. Louis	MN	140 ft	141 acres	23.1 ft
45	Whitefish Lake	Crow Wing	MN	138 ft	7,714 acres	14.4 ft
46	Rose Lake	Otter Tail	MN	137 ft	1,200 acres	16 ft
47	Long Lake	Hubbard	MN	135 ft	1,926 acres	11.2 ft
48	Big Sand Lake	Hubbard	MN	135 ft	1,639 acres	23 ft
49	Geneva Lake	Walworth	WI	135 ft	5,401 acres	21 ft
50	Kabekona Lake	Hubbard	MN	133 ft	2,433 acres	12.1 ft

Where to stay near the deepest lakes

Planning a trip to Minnesota or Wisconsin's deepest lakes? Jump to live cabin and hotel availability on each lake's page.

Frequently Asked Questions

Gilbert Pit Lake in St. Louis County, MN, is the deepest on our index at a maximum depth of 443 ft.

Maximum depth comes from state DNR bathymetric (depth-contour) surveys, which sound the lake bottom on a grid and record the deepest point. We report the official maximum depth from the most recent published survey. Some of the very deepest entries are flooded mine pits, which reach extreme depths in a small footprint.

Deep lakes stratify in summer: a warm surface layer floats on a cold bottom layer, and the two do not mix. That traps phosphorus released from bottom sediments down low, away from the sunlit surface where it would otherwise fuel algae. Deep lakes also have more water volume to dilute nutrient inputs, so they tend to stay clearer than shallow lakes of the same area.

Depth helps cold-water species. Lake trout, cisco, and whitefish need the cold, oxygen-rich water that only deep, stratified lakes hold through summer. Walleye and bass do well in lakes with a mix of deep basins and shallow structure. Very deep mine-pit lakes can be clear but biologically sparse, with limited shallow habitat.

Cleanest Lakes →Clearest Water →Largest Lakes →Best Fishing →

More on depth and water quality

Deepest Lakes in America and How Clean They Are

The deepest lakes with measurements on record, ranked by maximum depth with their nutrient and algae readings alongside. Depth helps on average — it does not decide the water.

Do Deeper Lakes Have Better Water Quality?

Surveyed maximum depth against nutrient and algae readings: the pattern, the shallow lakes that still read clean, and why land use beats bathymetry.

Are Reservoirs Cleaner Than Natural Lakes?

Dam-built reservoirs and natural lakes compared side by side on the same nutrient and algae measurements — the gap, the reasons behind it, and the exceptions.

Water Clarity Explained: What Secchi Depth Tells You

What a Secchi depth reading measures, how many feet counts as good clarity, and why clear water is not always clean — with readings from measured lakes.

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