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14-acre lake near Gwynedd. The lake tops out around 36 ft. What you see is a modeled chart: the shoreline is real, the max depth is published, and the contours between are estimated. Plan with it; don't navigate by it. Species by species, here's what the data says the year looks like.
On the chart, Llyn Cwm-mynach draws 14 acres inside 0.8 miles of shoreline. The shoreline is moderately structured (index 1.5) — enough points and pockets to pattern. Littoral water — the productive band under ~15 ft — makes up 56% of this chart, as modeled. Call it 0.3 mi long. The water lies in Gwynedd. The nearest mapped water is Llyn Dulyn, 1 mi to the west.
Come spring, look for brown trout tight to the bank in 3 to 25 ft. They move out to 11 to 36 ft in summer and finish the year down in 5 to 35 ft. If you only fish one area, make it Break off the point: a drop-off around 16 ft that scores prime in summer. Best bite is after dark and early morning. A spoon at the thermocline or a deep stickbait (night) 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 | 3 to 25 ft | dawn & dusk | Main-lake point (9 ft) | Stickbait off planer boards (shallow), Small spoon along mud lines |
| Summer | 11 to 36 ft chart-limited; documented 25 to 60 ft | night & dawn | Break off the point (16 ft) | Spoon at the thermocline, Deep stickbait (night) |
| Fall | 5 to 30 ft | dusk & dawn | Main-lake point (9 ft) | Jerkbait over gravel, Casting spoon |
| Winter | 5 to 35 ft | dawn | Break off the point (16 ft) | Jigging spoon, Small stickbait (slow) |
The spring pattern is a shallow one: european perch in 3 to 12 ft. Midsummer fish sit out in 8 to 28 ft before dropping to 12 to 33 ft for winter. The spot to know is Deep basin, a deep basin in about 31 ft of water that rates prime for european perch in fall. Plan around early morning in the warm months. Summer baits: a drop-shot micro plastics or a small crankbait (perch pattern) gets it done.
| Season | Depth | Best window | Start at | Go-to baits |
|---|---|---|---|---|
| Spring | 3 to 12 ft | midday & dawn | open water | Small jig + curly tail, Inline spinner #1-2 |
| Summer | 8 to 28 ft | dawn | Break off the point (16 ft) | Drop-shot micro plastics, Small crankbait (perch pattern) |
| Fall | 10 to 33 ft | midday | Deep basin (31 ft) | Jigging spoon (small), Drop-shot on deep flats |
| Winter | 12 to 33 ft | midday & dawn | Deep basin (31 ft) | Tungsten jig + maggots, Small balance jig |
Start shallow in spring: northern pike sit in 2 to 8 ft that time of year. Summer pushes them deeper, 8 to 20 ft, and winter fish settle into 5 to 15 ft. The spot to know is Break off the point, a drop-off in about 16 ft of water that rates prime for northern pike in fall. Warm-month bites cluster around early morning and the evening. Throw a bucktail or a weedless spoon over cabbage until the fish tell you otherwise.
| Season | Depth | Best window | Start at | Go-to baits |
|---|---|---|---|---|
| Spring | 2 to 8 ft | midday & dawn | open water | #5 inline spinner, Spoon (red/white) |
| Summer | 8 to 20 ft | dawn & dusk | Break off the point (16 ft) | Bucktail, Weedless spoon over cabbage |
| Fall | 6 to 18 ft | midday & dawn | Break off the point (16 ft) | Big rubber (Bull Dawg style), Husky-style jerkbait |
| Winter | 5 to 15 ft | midday | Main-lake point (9 ft) | Tip-ups, Large jigging spoon |
Early season arctic char use the shallows, holding in 4 to 15 ft. Expect a summer slide to 11 to 36 ft, then a winter hold in 9 to 36 ft. Put Deep basin first on the milk run — a deep basin near 31 ft that grades prime for summer. In summer the feeding windows fall in early morning. Tie on a jigging spoon vertical or a tube jig (smelt) and you're in the game.
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 | midday & dawn | Break off the point (16 ft) | Small casting spoon (silver/orange), Jerkbait (small) |
| Summer | 11 to 36 ft chart-limited; documented 20 to 60 ft | dawn | Deep basin (31 ft) | Jigging spoon vertical, Tube jig (smelt) |
| Fall | 8 to 30 ft | midday & dusk | Break off the point (16 ft) | Casting spoon (orange/gold), Beadhead streamer |
| Winter | 9 to 36 ft chart-limited; documented 10 to 40 ft | midday & dawn | Deep basin (31 ft) | Jigging spoon (glow/silver), Tungsten jig + plastic |
Count 3 structure marks on this chart. The deepest, Deep basin, sits near 31 ft.
Llyn Cwm-mynach is about 36 ft (11 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 brown trout, european perch, northern pike, arctic char on Llyn Cwm-mynach. This isn't a survey of the water — none is published for it — but an informed estimate from the species common to the region, narrowed by this water's depth, size and each species' range.
Deep basin is the top-rated area: a deep basin in about 31 ft of water that rates prime for european perch in fall. The map above holds the full rated-spot list for every species and season.
For brown trout, the summer bite is best in after dark and early morning. Each species page section below lists the seasonal windows, and the map shows a live NOW badge when you're inside one.
Llyn Dulyn 1 mi · Llyn y Bi 2 mi · Llyn Bodlyn 2 mi · Llyn Hywel 2 mi · Llyn Erddyn 3 mi · Gloyw Lyn 4 mi · Llyn Gwernan 5 mi · Llyn Cwm Bychan 5 mi · Llyn y Gadair 7 mi · Llyn Cau 7 mi · Llyn Trawsfynydd 8 mi · Llyn Llenyrch 9 mi
See how Llyn Cwm-mynach stacks up: best northern pike lakes in United Kingdom · best european perch lakes in United Kingdom · best brown trout lakes in United Kingdom · best arctic char lakes in United Kingdom
More water nearby: Gwynedd fishing maps (35 charts). Browse all United Kingdom 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.