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Rating depth structure for lake sturgeon.
Recent public catches load as you reach this section.
71-acre lake in Thunder Bay District, Ontario. The lake tops out around 53 ft. Bathymetry on this water is estimated from its real outline and maximum depth. Use it to shortlist water, then verify with your electronics — and never navigate by it. Every species below gets its seasonal read from the same numbers driving the chart.
The outline encloses 71 acres, worked by 1.6 miles of shoreline. At index 1.4 the outline is almost a bowl — read the depth changes, not the shoreline. Roughly 15% of the water is 15 ft or less as modeled, the band where the food chain lives. Figure 0.7 mi of water from one end to the other, 0.3 mi at the beam. Thunder Bay District claims this one. Its nearest charted neighbour, Marie Louise Lake, is 3 mi to the north.
Start shallow in spring: lake sturgeon sit in 3 to 15 ft that time of year. Summer pushes them deeper, 15 to 40 ft, and winter fish settle into 16 to 53 ft. The spot to know is Deep basin, a deep basin in about 45 ft of water that rates prime for lake sturgeon in fall. Warm-month bites cluster around after dark and the evening.
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 | 3 to 15 ft | dusk & night | open water | |
| Summer | 15 to 40 ft | night & dusk | Deep basin (45 ft) | |
| Fall | 15 to 45 ft | dusk | Deep basin (45 ft) | |
| Winter | 16 to 53 ft chart-limited; documented 20 to 60 ft | midday | Deep basin (45 ft) |
5 pieces of structure are mapped here — Deep basin, around 45 ft, is the deepest of them.
Access data: OpenStreetMap contributors (ODbL) — community-mapped launches. Confirm conditions and fees locally before you launch.
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 Surprise Lake specifically, so confirm the current rules before you fish.
Check the official Ontario fishing regulations →
Surprise Lake is about 53 ft (16 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 sturgeon on Surprise Lake.
Deep basin is the top-rated area: a deep basin in about 45 ft of water that rates prime for lake sturgeon in fall. Scroll up to the map for the complete spot list by species and season.
For lake sturgeon, the summer bite is best in after dark 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 Surprise 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.
Marie Louise Lake 3 mi · Gardner Lake 6 mi · Twinpine Lake 6 mi · Norwegian Lake 7 mi · Lizard Lake 11 mi · Pounsford Lake 11 mi · Milkshake Lake 12 mi · Pass Lake 16 mi · Upper Pass Lake 17 mi · Boulevard Lake 19 mi · D'Arcy Lake 19 mi · Mirror Lake 20 mi
See how Surprise Lake stacks up: best lake sturgeon 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.