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33-acre lake near Gwynedd. The lake tops out around 48 ft. This chart interpolates between a real shoreline and a known maximum depth. It will point you at likely water, but it is not a navigation product. The rest of this page walks each species through its year, using the map's own scoring.
Llyn Cwm Bychan maps at 33 acres behind 1.2 miles of shoreline. With a 1.5 development index there's bank structure worth casting at, in moderation. Littoral water — the productive band under ~15 ft — makes up 47% of this chart, as modeled. The basin spans about 0.5 mi end to end and 0.2 mi across at its widest. It sits in Gwynedd. If the bite dies, Gloyw Lyn is 1 mi to the southeast.
In spring, brown trout run shallow here, mostly 3 to 25 ft. Midsummer fish sit out in 14 to 48 ft before dropping to 5 to 35 ft for winter. Summer brown trout concentrate at Break off the point, a prime-rated drop-off around 22 ft. Fish it in after dark and early morning and you'll meet the bite. You won't need more than a spoon at the thermocline or a deep stickbait (night) most summer days.
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 (12 ft) | Stickbait off planer boards (shallow), Small spoon along mud lines |
| Summer | 14 to 48 ft chart-limited; documented 25 to 60 ft | night & dawn | Break off the point (22 ft) | Spoon at the thermocline, Deep stickbait (night) |
| Fall | 5 to 30 ft | dusk & dawn | Main-lake point (12 ft) | Jerkbait over gravel, Casting spoon |
| Winter | 5 to 35 ft | dawn | Break off the point (22 ft) | Jigging spoon, Small stickbait (slow) |
Spring european perch on Llyn Cwm Bychan hold shallow, usually 3 to 12 ft. They move out to 8 to 28 ft in summer and finish the year down in 12 to 33 ft. Put Shallow bay flat first on the milk run — a weed flat near 6 ft that grades prime for spring. The feeding windows run early morning. The summer box starts with a drop-shot micro plastics or a small crankbait (perch pattern).
| 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, Inline spinner #1-2 |
| Summer | 8 to 28 ft | dawn | Break off the point (22 ft) | Drop-shot micro plastics, Small crankbait (perch pattern) |
| Fall | 10 to 33 ft | midday | Break off the point (22 ft) | Jigging spoon (small), Drop-shot on deep flats |
| Winter | 12 to 33 ft | midday & dawn | Break off the point (22 ft) | Tungsten jig + maggots, Small balance jig |
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 6 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 (6 ft) | #5 inline spinner, Spoon (red/white) |
| Summer | 8 to 20 ft | dawn & dusk | Shallow bay flat (6 ft) | Bucktail, Weedless spoon over cabbage |
| Fall | 6 to 18 ft | midday & dawn | Shallow bay flat (6 ft) | Big rubber (Bull Dawg style), Husky-style jerkbait |
| Winter | 5 to 15 ft | midday | Shallow bay flat (6 ft) | Tip-ups, Large jigging spoon |
Start shallow in spring: arctic char sit in 4 to 15 ft that time of year. Summer pushes them deeper, 14 to 48 ft, and winter fish settle into 10 to 40 ft. The spot to know is Deep basin, a deep basin in about 41 ft of water that rates prime for arctic char in summer. Warm-month bites cluster around early morning. Throw a jigging spoon vertical or a tube jig (smelt) until the fish tell you otherwise.
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 | open water | Small casting spoon (silver/orange), Jerkbait (small) |
| Summer | 14 to 48 ft chart-limited; documented 20 to 60 ft | dawn | Deep basin (41 ft) | Jigging spoon vertical, Tube jig (smelt) |
| Fall | 8 to 30 ft | midday & dusk | Break off the point (22 ft) | Casting spoon (orange/gold), Beadhead streamer |
| Winter | 10 to 40 ft | midday & dawn | Deep basin (41 ft) | Jigging spoon (glow/silver), Tungsten jig + plastic |
Structure-wise the chart holds 5 features, led in depth by Deep basin at roughly 41 ft.
Llyn Cwm Bychan is about 48 ft (15 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 Bychan. 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.
Shallow bay flat is the top-rated area: a weed flat in about 6 ft of water that rates prime for european perch in spring. Every other rated spot, per species and season, is on the map above.
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.
Gloyw Lyn 1 mi · Llyn Hywel 3 mi · Llyn y Bi 3 mi · Llyn Tecwyn Isaf 4 mi · Llyn Llenyrch 4 mi · Llyn Dulyn 4 mi · Llyn Trawsfynydd 5 mi · Llyn Bodlyn 5 mi · Llyn Cwm-mynach 5 mi · Llyn Erddyn 6 mi · Llyn Du 8 mi · Llyn y Garn 8 mi
See how Llyn Cwm Bychan 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.