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74-acre lake in Thunder Bay District, Ontario. The lake tops out around 32 ft. The chart is a model: real shoreline, published maximum depth, interpolated in between. A planning tool, never a navigation product. What follows comes from the same scoring engine that paints the spots above.
On the chart, Mary Lake draws 75 acres inside 4.5 miles of shoreline. An index of 3.7 puts the bank firmly in maze territory: point after pocket after cove, every one a casting target. Littoral water — the productive band under ~15 ft — makes up 85% of this chart, as modeled. End to end it runs roughly 2 mi, about 0.2 mi across. You'll find it in Thunder Bay District. Closest neighbour on DepthScout: Two Island Lake, 3 mi southwest of here.
Come spring, look for lake whitefish tight to the bank in 10 to 32 ft. Through summer count on 10 to 32 ft; the winter hold is 10 to 32 ft. If you only fish one area, make it Deep basin: a deep basin around 27 ft that scores prime in summer. Best bite is early morning. A blade bait vertical or a small jigging spoon is the honest summer answer here.
Depth note: when a documented seasonal range extends below this chart, the table shows the deepest mapped working water, not a verified holding depth.
| Season | Depth | Best window | Start at | Go-to baits |
|---|---|---|---|---|
| Spring | 10 to 32 ft chart-limited; documented 15 to 45 ft | midday & dawn | Break off the point (14 ft) | Small jig + waxworm, Blade bait (small) |
| Summer | 10 to 32 ft chart-limited; documented 40 to 90 ft | dawn | Deep basin (27 ft) | Blade bait vertical, Small jigging spoon |
| Fall | 8 to 30 ft | dusk | Break off the point (14 ft) | Small spoon (gold), Jig + plastic larva |
| Winter | 10 to 32 ft chart-limited; documented 25 to 70 ft | midday & dawn | Deep basin (27 ft) | Jigging spoon + bead chain, Tungsten jig + waxie |
Spring walleye on Mary Lake hold shallow, usually 4 to 15 ft. By summer they slide out to 10 to 32 ft, and by winter most fish are in 10 to 32 ft. The chart's best answer is Break off the point — drop-off, 14 ft, prime for fall. Prime time lands in the evening and early morning. The summer box starts with a crawler harness on bottom bouncer or a deep crankbait (trolled).
Depth note: when a documented seasonal range extends below this chart, the table shows the deepest mapped working water, not a verified holding depth.
| Season | Depth | Best window | Start at | Go-to baits |
|---|---|---|---|---|
| Spring | 4 to 15 ft | dusk & dawn | Main-lake point (8 ft) | 1/8 oz jig + minnow, Hair jig |
| Summer | 10 to 32 ft chart-limited; documented 15 to 35 ft | dusk & dawn | Break off the point (14 ft) | Crawler harness on bottom bouncer, Deep crankbait (trolled) |
| Fall | 10 to 32 ft chart-limited; documented 12 to 40 ft | dusk & night | Break off the point (14 ft) | Jigging rap, Jig + big minnow |
| Winter | 10 to 32 ft chart-limited; documented 20 to 40 ft | dusk & dawn | Deep basin (27 ft) | Jigging spoon + minnow head, Rattle bait |
In spring, northern pike run shallow here, mostly 2 to 8 ft. Midsummer fish sit out in 8 to 20 ft before dropping to 5 to 15 ft for winter. Spring northern pike concentrate at Shallow bay flat, a prime-rated weed flat around 4 ft. Fish it in early morning and the evening and you'll meet the bite. You won't need more than a bucktail or a weedless spoon over cabbage most summer days.
| Season | Depth | Best window | Start at | Go-to baits |
|---|---|---|---|---|
| Spring | 2 to 8 ft | midday & dawn | Shallow bay flat (4 ft) | #5 inline spinner, Spoon (red/white) |
| Summer | 8 to 20 ft | dawn & dusk | Break off the point (14 ft) | Bucktail, Weedless spoon over cabbage |
| Fall | 6 to 18 ft | midday & dawn | Break off the point (14 ft) | Big rubber (Bull Dawg style), Husky-style jerkbait |
| Winter | 5 to 15 ft | midday | Shallow bay flat (4 ft) | Tip-ups, Large jigging spoon |
The chart marks 6 structure features on Mary Lake; the deepest is Deep basin at about 27 ft.
Season dates, license requirements, and size and bag limits for Ontario waters are set by the Ontario fishing regulations (FMZ summary) — and special regulations can apply to Mary Lake specifically, so confirm the current rules before you fish.
Check the official Ontario fishing regulations →
Mary Lake is about 32 ft (10 m) deep at its deepest point. The contours here are modeled from the water's real shape and maximum depth, so treat them as a rough guide.
Anglers target lake whitefish, walleye, northern pike on Mary Lake.
Deep basin is the top-rated area: a deep basin in about 27 ft of water that rates prime for lake whitefish in summer. Open the map above to see every rated spot for each species and season.
For lake whitefish, the summer bite is best in early morning. Each species page section below lists the seasonal windows, and the map shows a live NOW badge when you're inside one.
Fishing on Mary Lake is regulated by the Ontario fishing regulations (FMZ summary). Check the official Ontario regulations for current license requirements, season dates, and size and bag limits — special regulations can apply to this specific water.
Two Island Lake 3 mi · Halfway Lake 3 mi · Island Lake 4 mi · Wartman Lake 4 mi · Warnica Lake 5 mi · Greenhue Lake 5 mi · Barnum Lake 6 mi · Hawkeye Lake 6 mi · Trout Lake 7 mi · Surprise Lake 7 mi · Greenpike Lake 7 mi · Hazelwood Lake 9 mi
See how Mary Lake stacks up: best walleye lakes in Ontario · best northern pike lakes in Ontario · best lake whitefish lakes in Ontario
More water nearby: Thunder Bay District fishing maps (662 charts). Browse all Ontario fishing maps. See every water on DepthScout. How we build these maps. Fish here with a sonar unit that logs? Send us your depth data and we'll improve this chart, credited to you. For fishing guidance only, never navigation.