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127-acre lake in Cochrane District, Ontario. The lake tops out around 61 ft. The depth chart comes from Ontario Ministry of Natural Resources and Forestry bathymetric survey data, so the contours are survey-derived rather than computer-modeled. What the data behind the map says about each species, season by season:
Marathon Lake maps at 126 acres behind 2.9 miles of shoreline. With a 1.8 development index there's bank structure worth casting at, in moderation. About 55% of the surface sits shallower than 15 ft — that's the weed-and-bait zone. The basin spans about 0.7 mi end to end and 0.5 mi across at its widest. It sits in Cochrane District. Trusz L. sits 1 mi east — the closest neighbouring chart.
Start shallow in spring: lake whitefish sit in 15 to 45 ft that time of year. Summer pushes them deeper, 18 to 61 ft, and winter fish settle into 18 to 61 ft. The spot to know is Deep basin, a deep basin in about 60 ft of water that rates prime for lake whitefish in summer. Warm-month bites cluster around early morning. Throw a blade bait vertical or a small jigging spoon until the fish tell you otherwise.
| Season | Depth | Best window | Start at | Go-to baits |
|---|---|---|---|---|
| Spring | 15 to 45 ft | midday & dawn | Break off the point (40 ft) | Small jig + waxworm, Blade bait (small) |
| Summer | 18 to 61 ft | dawn | Deep basin (60 ft) | Blade bait vertical, Small jigging spoon |
| Fall | 8 to 30 ft | dusk | open water | Small spoon (gold), Jig + plastic larva |
| Winter | 18 to 61 ft | midday & dawn | Deep basin (60 ft) | Jigging spoon + bead chain, Tungsten jig + waxie |
Spring puts sauger in skinny water — 4 to 18 ft is the zone. As the season builds they drop to 10 to 30 ft, wintering in 15 to 45 ft. Winter sauger concentrate at Break off the point, a prime-rated drop-off around 40 ft. Warm-month bites cluster around early morning and the evening. A bottom bouncer + crawler or a 3-way rig with stickbait covers the summer program.
| Season | Depth | Best window | Start at | Go-to baits |
|---|---|---|---|---|
| Spring | 4 to 18 ft | dawn & dusk | Main-lake point (1 ft) | 3/8 oz jig + ringworm, Hair jig + minnow |
| Summer | 10 to 30 ft | dawn & dusk | open water | Bottom bouncer + crawler, 3-way rig with stickbait |
| Fall | 12 to 35 ft | dusk & dawn | Break off the point (40 ft) | Jig + big minnow, Blade bait |
| Winter | 15 to 45 ft | dusk | Break off the point (40 ft) | Heavy jigging spoon, Jig + minnow (vertical) |
When the water first warms, northern pike slide up into 2 to 8 ft. Summer is an 8 to 20 ft game here, winter a 5 to 15 ft one. Start at Shallow bay flat. It's a weed flat holding about 1 ft of water and rates prime come spring. The feeding windows run early morning and the evening. Keep a bucktail or a weedless spoon over cabbage rigged through the warm months.
| Season | Depth | Best window | Start at | Go-to baits |
|---|---|---|---|---|
| Spring | 2 to 8 ft | midday & dawn | Shallow bay flat (1 ft) | #5 inline spinner, Spoon (red/white) |
| Summer | 8 to 20 ft | dawn & dusk | Shallow bay flat (1 ft) | Bucktail, Weedless spoon over cabbage |
| Fall | 6 to 18 ft | midday & dawn | Shallow bay flat (1 ft) | Big rubber (Bull Dawg style), Husky-style jerkbait |
| Winter | 5 to 15 ft | midday | Shallow bay flat (1 ft) | Tip-ups, Large jigging spoon |
Marathon Lake carries 6 mapped structure features, topping out (or rather bottoming out) at Deep basin, about 60 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 Marathon Lake specifically, so confirm the current rules before you fish.
Check the official Ontario fishing regulations →
Marathon Lake is about 61 ft (19 m) deep at its deepest point. The depth chart comes from Ontario Ministry of Natural Resources and Forestry bathymetric survey data, so the contours are survey-derived rather than computer-modeled.
Anglers target lake whitefish, sauger, northern pike on Marathon Lake.
Deep basin is the top-rated area: a deep basin in about 60 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 Marathon 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.
Trusz L. 1 mi · Mary L. 1 mi · Mirky L. 1 mi · Cooke L. 1 mi · Dungg L. 2 mi · Marilyn L. 2 mi · Anne L. 2 mi · Watton L. 4 mi · Lake 12L-17 4 mi · Upper Bingle Lake 4 mi · Packsack L. 5 mi · Lake 12L-12 5 mi
See how Marathon Lake stacks up: best sauger lakes in Ontario · best northern pike lakes in Ontario · best lake whitefish lakes in Ontario
More water nearby: Cochrane District fishing maps (673 charts). Browse all Ontario fishing maps or see every water on DepthScout. Bathymetry: published agency survey data. 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.