Lakes / Illinois / Lake County / Saint Marys Lake
Saint Marys Lake, Illinois
105.51 acres
Surface Area
Where It Sits, and How Deep It Goes
Locator - Illinois
42.28 degrees N, 87.99 degrees W - Lake County. State and county outlines drawn from Census boundary data; the lake marker is placed by its USGS National Hydrography Dataset coordinates, not by eye. Schematic - not a survey map.
How Saint Marys Lake Stacks Up
- Larger than 62% of the 511 lakes counted in Illinois.
- About 33 miles from Chicago, as the crow flies.
Lakes Nearby
| Lake | County | Distance | Surface Area |
|---|---|---|---|
| Loch Lomond | Lake | 1.0 mi | 75.12 acres |
| Lake Charles | Lake | 2.1 mi | 38.8 acres |
| Diamond Lake | Lake | 2.3 mi | 152.46 acres |
| Minear Lake | Lake | 2.5 mi | 81.79 acres |
| Liberty Lake | Lake | 2.6 mi | 32.12 acres |
| Countryside Lake | Lake | 3.4 mi | 140.85 acres |
Straight-line distance between lake centers.
Facts and Figures
Questions About Saint Marys Lake
How Big Is Saint Marys Lake?
Saint Marys Lake covers 105.51 acres in Lake County, Illinois.
What Is the Largest Lake in Lake County?
Nippersink Lake is the largest lake in Lake County, at 2,492.93 acres.
Largest Lakes in Illinois
| # | Lake | County | Surface Area | Max Depth |
|---|---|---|---|---|
| 1 | Carlyle Lake | Clinton | 22,796.77 acres | - |
| 2 | Mine Number 21 Reservoir | Franklin | 17,062.04 acres | - |
| 3 | Upper Peoria Lake | Woodford | 15,460.64 acres | - |
| 4 | Lake Shelbyville | Shelby | 10,235.1 acres | - |
| 5 | Crab Orchard Lake | Williamson | 7,292.57 acres | - |
All 511 Illinois lakes ranked by surface area
Sources: USGS National Hydrography Dataset (The National Map) lake data (ID 109984490). Verified October 30, 2026.