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212-acre lake in Algoma District, Ontario. The lake tops out around 79 ft. The depth data here comes from the Ontario MNRF survey of 1981 (a transect sounding survey). Here's the year, species by species, as the scoring engine sees it.
On the chart, Rosemarie Lake draws 213 acres inside 3.7 miles of shoreline. Index 1.8 on the shoreline: a few honest points and pockets, nothing labyrinthine. Roughly 33% of the water is 15 ft or less, the band where the food chain lives. The basin spans about 1.4 mi end to end and 0.5 mi across at its widest. The water lies in Algoma District. Closest neighbour on DepthScout: Sister Lake, 2 mi southwest of here.
Start shallow in spring: lake trout sit in 10 to 40 ft that time of year. Summer pushes them deeper, 24 to 79 ft, and winter fish settle into 20 to 79 ft. The spot to know is Deep basin, a deep basin in about 79 ft of water that rates prime for lake trout in summer. Warm-month bites cluster around early morning. Throw a white tube jig (deep) or a magnum spoon on downrigger until the fish tell you otherwise.
| Season | Depth | Best window | Start at | Go-to baits |
|---|---|---|---|---|
| Spring | 10 to 40 ft | dawn & dusk | Main-lake point (12 ft) | Casting spoon over shoals, Jerkbait (shallow) |
| Summer | 24 to 79 ft | dawn | Deep basin (79 ft) | White tube jig (deep), Magnum spoon on downrigger |
| Fall | 10 to 50 ft | dusk & dawn | Main-lake point (12 ft) | Heavy casting spoon, Jigging rap over reefs |
| Winter | 20 to 79 ft | dawn | Deep basin (79 ft) | White tube jig, Airplane jig |
Spring yellow perch on Rosemarie Lake hold shallow, usually 3 to 12 ft. By summer they slide out to 10 to 30 ft, and by winter most fish are in 15 to 35 ft. The chart's best answer is Shallow bay flat — weed flat, 6 ft, prime for spring. Prime time lands in early morning. The summer box starts with a drop-shot micro plastics or a small spoon tipped with worm.
| Season | Depth | Best window | Start at | Go-to baits |
|---|---|---|---|---|
| Spring | 3 to 12 ft | midday & dawn | Shallow bay flat (6 ft) | Small jig + curly tail, Perch-pattern micro crank |
| Summer | 10 to 30 ft | dawn | Break off the point (28 ft) | Drop-shot micro plastics, Small spoon tipped with worm |
| Fall | 12 to 35 ft | midday | Break off the point (28 ft) | Jigging spoon (small), Perch rig / spreader |
| Winter | 15 to 35 ft | midday & dawn | Break off the point (28 ft) | Tungsten jig + spikes, Rattle spoon (small) |
Rosemarie Lake carries 6 mapped structure features, topping out (or rather bottoming out) at Deep basin, about 79 ft down.
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 Rosemarie Lake specifically, so confirm the current rules before you fish.
Check the official Ontario fishing regulations →
Rosemarie Lake is about 79 ft (24 m) deep at its deepest point. The depth data here comes from the Ontario MNRF survey of 1981 (a transect sounding survey).
Anglers target lake trout, yellow perch on Rosemarie Lake.
Deep basin is the top-rated area: a deep basin in about 79 ft of water that rates prime for lake trout in summer. Scroll up to the map for the complete spot list by species and season.
For lake trout, 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 Rosemarie 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.
Sister Lake 2 mi · Skunk Lake 3 mi · Rawhide Lake 3 mi · Bilton Lake 4 mi · Alexander Lake 5 mi · Applesauce Lake 5 mi · Burnt Lake 5 mi · Terace L. 5 mi · Moon Lake 6 mi · Moccasin Lake 6 mi · Nina Lake 6 mi · Harry Lake 7 mi
See how Rosemarie Lake stacks up: best yellow perch lakes in Ontario · best lake 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.