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364-acre lake in Algoma District, Ontario. The lake tops out around 120 ft. The depth data here comes from the Ontario MNRF survey of 1968, a decades-old survey (a transect sounding survey). Below is the species-by-species picture, pulled from the same data the map uses.
On the chart, Mamainse Lake draws 366 acres inside 5.9 miles of shoreline — 3 islands included. An index of 2.2 puts the bank firmly in maze territory: point after pocket after cove, every one a casting target. The shallow band under 15 ft claims about 19% of the surface — that's where the groceries are. Tip to tip the water measures near 1.9 mi with a 0.8-mi widest point. The water lies in Algoma District. For a second option, Cedar Lakes lies 2 mi east.
Spring puts brook trout in skinny water — 2 to 15 ft is the zone. Warm water sends them out to 10 to 30 ft; cold water stacks them in 3 to 20 ft. Main-lake point is the standout, a point at roughly 1 ft, rated prime for spring brook trout. Plan around early morning and the evening in the warm months. A small spoon fished deep or a trolled lake-clear wobbler + worm covers the summer program.
| Season | Depth | Best window | Start at | Go-to baits |
|---|---|---|---|---|
| Spring | 2 to 15 ft | dawn & dusk | Main-lake point (1 ft) | Small inline spinner (gold), Tiny spoon |
| Summer | 10 to 30 ft | dawn & dusk | open water | Small spoon fished deep, Trolled lake-clear wobbler + worm |
| Fall | 2 to 15 ft | midday & dawn | Main-lake point (1 ft) | Small spoon (orange), Spinner |
| Winter | 3 to 20 ft | dawn | Shallow bay flat (1 ft) | Small jigging spoon, Tungsten jig + plastic |
In spring, lake trout run shallow here, mostly 10 to 40 ft. Summer pushes them deeper, 50 to 120 ft, and winter fish settle into 20 to 80 ft. Deep basin is the standout, a deep basin at roughly 119 ft, rated prime for summer lake trout. Time it for early morning. You won't need more than a white tube jig (deep) or a magnum spoon on downrigger most summer days.
| Season | Depth | Best window | Start at | Go-to baits |
|---|---|---|---|---|
| Spring | 10 to 40 ft | dawn & dusk | Main-lake point (1 ft) | Casting spoon over shoals, Jerkbait (shallow) |
| Summer | 50 to 120 ft | dawn | Deep basin (119 ft) | White tube jig (deep), Magnum spoon on downrigger |
| Fall | 10 to 50 ft | dusk & dawn | Main-lake point (1 ft) | Heavy casting spoon, Jigging rap over reefs |
| Winter | 20 to 80 ft | dawn | Break off the point (70 ft) | White tube jig, Airplane jig |
The chart marks 6 structure features on Mamainse Lake; the deepest is Deep basin at about 119 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 Mamainse Lake specifically, so confirm the current rules before you fish.
Check the official Ontario fishing regulations →
Mamainse Lake is about 120 ft (37 m) deep at its deepest point. The depth data here comes from the Ontario MNRF survey of 1968, a decades-old survey (a transect sounding survey).
Anglers target brook trout, lake trout on Mamainse Lake.
Deep basin is the top-rated area: a deep basin in about 119 ft of water that rates prime for lake trout in summer. Every other rated spot, per species and season, is on the map above.
For brook trout, the summer bite is best in early morning and the evening. Each species page section below lists the seasonal windows, and the map shows a live NOW badge when you're inside one.
Fishing on Mamainse 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.
Cedar Lakes 2 mi · Upper Smith Lake 2 mi · Gimlet Lake 2 mi · Brant Lake 2 mi · Pancake Lake 3 mi · Middle Pancake Lake 5 mi · Nicolet L. 16 5 mi · Upper Pancake Lake 5 mi · Annie Lake 6 mi · Wiley Lake 6 mi · Pipe Lake 6 mi · West Joco Lake 7 mi
See how Mamainse Lake stacks up: best lake trout lakes in Ontario · best brook trout lakes in Ontario
More water nearby: Algoma District fishing maps (1026 charts). Browse all Ontario fishing maps or see every water on DepthScout. Bathymetry credit: state fisheries survey programs. 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.