Stillwater · Ordovician Volcanics · Wales / Snowdonia (Blaenau Ffestiniog uplands), GB-WLS

Llyn Cwmorthin

Misty mountain lake (Llyn Cwmorthin) reflecting snow-capped cliffs in Snowdonia, north Wales.

Cwmorthin is the water Cambrian AA members talk about first — an old slate-valley lake with a genuine claim to fame, a seven-pound-two brown trout taken from it back in 1922 and still cited whenever the club wants to make a point about what's possible here.

Fair · Trout
Minkie · 6-10
Fairlive now
Buzzer expected on Llyn Cwmorthin
Good wave on — drift country. A useful wave. Work the productive shore.
60% confidence

Llyn Cwmorthin is often best in spring through autumn.

What moved it
  • WindW 9 km/hLight breeze · Gusts to 21 km/h
Today's fly
Minkie
Minkie6-10
Retrieve, sub-surface
Conditions on the water
Estimate
Wind
Light breeze · Gusts to 21 km/h
W 9 km/h
N
W
from the west
WaveRipple
Water temp10.0°C
Air temp14°C
CloudOvercast
Pressure1017 hPa
Rain · recent0.0 mm

No gauge on this water — readings are regional estimates from weather, not a live gauge.

Head to
Wind driftSW wind
North-eastern end

A southwesterly has held for the best part of three days, running warmer than the water (13°C air against 10°C water). Expect fish at the north-eastern end — the bank it is blowing into — where the drift piles food, colour and warmth together. This reads the upper water, though — a bottom bait at range feels it far less than a floater or a fish in the margins. Treat it as a tiebreaker between good swims rather than an override — features and angling pressure usually count for more.

How to fish it · for Trout
When
Late April–June; evening rises through summer
Where
Set up a broadside drift and cover the water systematically. Work a bushy searching pattern on the bob and drop a contrasting nymph on the point.
The plan
Plan A

Set up a broadside drift and cover the water systematically. Work a bushy searching pattern on the bob and drop a contrasting nymph on the point.

Plan B

If the main plan is not working, switch to a smaller, more imitative pattern fished slower and deeper. A change of drift angle can also make a difference.

Watch for

Watch for Sedge towards evening — this could be the best window of the day.

Bank

Bank-only venue. Fish from accessible margins, points, weed edges, and inflows.

Sub-surface · on the nymphunder the surface

Hatch predictions

Top nymph shown — see all 2 guilds as a supporter.

Start free trial

14-day free trial. Cancel anytime.

Beyond the hatch · worth watchingambient prey(1)

Hatch predictions

Top prey shown — see all 5 as a supporter.

Start free trial

14-day free trial. Cancel anytime.

Through the year
0–3 scale · October highlighted
J
F
M
A
M
J
J
A
S
O
N
D
Heather FlyHatch
2
2
Daddy Long LegsHatch
2
3
2
Claret DunHatch
2
3
2
Murrough (Great Red Sedge)Hatch
2
3
2

Numbers are intensity 0 (none) to 3 (peak) — a guide, not a guarantee.

Ranked for today
Trout fly box
Bays & launches · 1
Day ticket via Cambrian Angling AssociationAccess varies
The club's flagship historic water in an old slate valley, holding a strong wild brown trout stock; covered by the Cambrian AA's single day ticket across the whole llyn portfolio.
Visit official site ↗
What's coming
Plan ahead
5-day outlook
Condition match
73%
Cloud50%
Wind100%
Temp60%

A good match for Llyn Cwmorthin — most conditions are close to what it fishes best in.

Other water nearby · 5
Gallery · 2
  1. Misty mountain lake (Llyn Cwmorthin) reflecting snow-capped cliffs in Snowdonia, north Wales.
    Llyn Cwmorthin
  2. Terrain map of the venue
    Terrain map
About this water

Cwmorthin is the water Cambrian AA members talk about first — an old slate-valley lake with a genuine claim to fame, a seven-pound-two brown trout taken from it back in 1922 and still cited whenever the club wants to make a point about what's possible here. You won't catch that fish again, obviously, but the stock behind it has stayed strong, and there's a weight of history sitting on this water that the smaller llyns simply don't carry. Fish it on a day with some cloud and a breeze, work the margins where the old quarry spoil meets deeper water, and treat the 1922 fish as folklore worth knowing rather than a target.

  • Lake
  • Ordovician volcanics
Why this score
  • Wind conditions (ripple) closely match what this water fishes best in.
  • Buzzer is in its seasonal window, boosting the chance of targeted feeding.
Related guides
Casting instructors near here
Booking & contacts
Boards & regulators