What Is the Deepest Lake in Minnesota?
Lake Superior, which forms Minnesota's northeast border, is the deepest lake touching the state at 1,332 ft. Among lakes entirely within Minnesota, Gilbert Pit Lake in St. Louis County is the deepest at 443 feet. Below: the 25 deepest monitored lakes entirely within Minnesota, ranked by maximum depth.
Top 25 Deepest Inland Lakes in Minnesota
Ranked by maximum recorded depth (feet). Water quality grade shown for each.
- 1. Gilbert Pit Lake — 443 ft (St. Louis County, Grade B)
- 2. St James Pit Lake — 381 ft (St. Louis County, Grade A)
- 3. Iron Chief Complex Lake — 262.1 ft (St. Louis County, Grade A)
- 4. Lasalle Lake — 213 ft (Hubbard County, Grade B)
- 5. Watap Lake — 210 ft (Cook County, Grade C)
- 6. Gabimichigami Lake — 209 ft (Cook County, Grade B)
- 7. Ten Mile Lake — 208 ft (Cass County, Grade A)
- 8. Loon Lake — 202 ft (Cook County, Grade A)
- 9. Gunflint Lake — 200 ft (Cook County, Grade A)
- 10. Little Gunflint Lake — 200 ft (Cook County, Grade A)
- 11. Strup Lake — 195 ft (Lake County, Grade C)
- 12. Sand Point Lake — 184 ft (St. Louis County, Grade C)
- 13. Sand Point Lake — 184 ft (St. Louis County, Grade D)
- 14. Sand Point Lake — 184 ft (St. Louis County, Grade D)
- 15. Larson Lake — 177 ft (Itasca County, Grade A)
- 16. Lac la Croix Lake — 168 ft (St. Louis County, Grade C)
- 17. Crooked Lake — 165 ft (Lake County, Grade C)
Why Deep Lakes Matter
Depth is one of the strongest predictors of lake water quality. Deep lakes thermally stratify in summer, isolating cold, oxygen-rich bottom water (the hypolimnion) from warm surface water. This protects coldwater fish like trout and cisco, and limits the internal phosphorus cycling that drives algae blooms.
Most of Minnesota's deepest lakes are in the Arrowhead region — carved out by glaciers during the Wisconsin glaciation 12,000 years ago. The Boundary Waters Canoe Area Wilderness contains many of them.