Atlas of Wales

Conwy / Gwynedd boundary · Eryri · Mountain

Carnedd LlewelynCarneddau · 1,064 m

Two ridge routes reach a wide summit plateau: the Carneddau's highest ground. Real mountain walking, with no railway to soften it.

Choose your route Is today the day?

The Carneddau's highest point: a broad, boulder-strewn plateau above Ogwen, reached by two documented ridge routes: real mountain walking, not a marked family trail.

Height
1,064 m
Ways up
Two · Ogwen Horseshoe or Craig yr Ysfa
Commitment
Full day either way
Terrain
Boulder-strewn plateau and ridge
Exposure & navigation
Moderate–high on both

Choose your route

Two ways up. Both a full day.

There is no official Eryri National Park route page for Carnedd Llewelyn. Both lines below are real, documented ridge walks from Ogwen, assembled from independent route guides, not an official register. Pick one and the board below redraws to it.

Ways up

Over Pen yr Ole Wen and Carnedd Dafydd to Pen yr Helgi Du
Your line
  1. 1
    A5 layby, Llyn OgwenThe eastern-end layby start, via Cwm Lloer.
  2. 2
    Pen yr Ole Wen scrambleA rocky gully near the top of the ascent, widely described across independent guides. Not a walk.
  3. 3
    Bwlch yr Ole WenThe col between Pen yr Ole Wen and Carnedd Dafydd.
  4. 4
    Carnedd DafyddThe ridge's second summit, before the cliff-top traverse.
  5. 5
    Carnedd Llewelyn summitThe high point: a flat, boulder-strewn plateau.
  6. 6
    On to Pen yr Helgi DuVia Bwlch Eryl Farchog, with a further scramble, then down Y Braich to the A5.

Two independent route guides corroborate the core sequence of this route, but every distance and ascent figure here rests on a single source, shown with an "About" qualifier rather than as a settled figure.

  1. 1
    Ogwen CottagePast Llyn Ogwen to Idwal Cottage, then up the Tal-y-Llyn Ogwen path beside Afon Lloer.
  2. 2
    Pen yr Ole Wen scrambleThe same rocky-gully section as the Ogwen Horseshoe.
  3. 3
    Carnedd Dafydd, via Carnedd FachThe ridge's second summit.
  4. 4
    Carnedd Llewelyn summitThe high point: a flat, boulder-strewn plateau.
  5. 5
    Toward Craig yr YsfaThe ridge continues east above the cliffs.
  6. 6
    Craig yr Ysfa descentA second scramble section, down toward Ffynnon Llugwy reservoir, then back via the A5.

A single outdoor-editorial source describes this circuit in full; no ascent figure is published for it at all, so this guide states distance and duration only, never an invented ascent.

Practical brief

Your route in practice:

The classic four-summit line, from the A5 layby.

Start point
A5 layby, eastern end of Llyn Ogwen (grid ref SH668605)
Parking / booking
No booking system. Roadside layby parking: fills early; further laybys along Llyn Ogwen. The managed Ogwen Centre car park is nearby, but its exact tariff varies between two Eryri NPA pages. Check the current price directly.
Public transport
The TrawsCymru T10 stops at Ogwen; the Bws Ogwen minibus from Bethesda publishes no fixed timetable. Check the current service before travelling.
Facilities
No toilets at the layby itself; the nearest are at the Cwm Idwal Centre, Ogwen.
Return / descent
No alternative escape has been verified for this guide. Reverse the ridge if you don't continue to Pen yr Helgi Du.
Avoid this route if
Poor visibility, wet or windy conditions, or you're not comfortable with a rocky scramble section and featureless summit navigation.

A longer day from Ogwen Cottage, with a second scramble on the way down.

Start point
Ogwen Cottage car park, A5 (pay and display)
Parking / booking
No booking system. Card/contactless only, no cash. Exact tariff varies between two Eryri NPA pages, so check the current price directly rather than relying on a figure here.
Public transport
The TrawsCymru T10 stops at Ogwen; the Bws Ogwen minibus from Bethesda publishes no fixed timetable. Check the current service before travelling.
Facilities
Toilets and showers at the Cwm Idwal Centre, 24-hour access.
Return / descent
No alternative escape has been verified for this guide. The Craig yr Ysfa scramble must be descended, not just climbed.
Avoid this route if
You're relying on the T10 or Bws Ogwen as a descent plan; both run to a timetable, at the roadside, not partway up the mountain.

Checked 17 July 2026 against Eryri National Park Authority and independent route guides. Confirm current parking, transport and ground conditions before you go.

Before you go

Need the exact mountain details?

Parking, transport, dogs, the routes, weather and emergency — checked before you go.

Parking & booking
  • A5 layby, Llyn Ogwen (Ogwen Horseshoe start): roadside layby parking around Llyn Ogwen; fills early, especially at weekends.
  • Ogwen Centre car park (Craig yr Ysfa Circuit start): Eryri NPA-managed, card/contactless only (no cash), 2 Blue Badge bays, EV charging. Two Eryri NPA pages give different daily tariffs for this car park. Check the current price directly rather than relying on a single figure. Open parking area (opens in a new tab).
  • Gerlan, Bethesda (northern approach, not detailed as a full route on this page): a small, informal lay-by, with overflow parking sometimes available in a local farmer's yard. Not NPA-managed.
  • Llyn Eigiau (eastern approach, not detailed as a full route on this page): a small free parking area at the road end above the reservoir (grid ref SH731662), reached by a narrow gated lane from Tal-y-Bont in the Conwy Valley. The gates are yours to open and close. This is the Conwy-side start, and the long way in: the published round from here is 16.3 km with 1,103 m of ascent. Not NPA-managed. Open parking area (opens in a new tab).

Details from Eryri National Park Authority: Ogwen (opens in a new tab) and Parking in Eryri (opens in a new tab). The Gerlan and Llyn Eigiau lay-bys are not National Park facilities; those details come from walkingbritain.co.uk (opens in a new tab), with the Llyn Eigiau parking point corroborated independently by go4awalk.

Public transport

The TrawsCymru T10 (opens in a new tab) (Bangor–Bethesda–Betws-y-Coed–Corwen) stops at Llyn Ogwen; Eryri National Park Authority names it as the way in. Partneriaeth Ogwen also runs the Bws Ogwen electric minibus from Bethesda, but it publishes no fixed timetable page. Check the current service before travelling.

Toilets, food & water

Toilets and showers, 24-hour access, at the Cwm Idwal Centre, Ogwen. The only on-site facilities either route passes. Nothing at the Gerlan approach, and nothing on the mountain itself on any line.

Dogs & livestock

Dogs must be kept on a lead of no more than 2 metres on Open Access Land between 1 March and 31 July (breeding season for livestock and ground-nesting birds). On public rights of way, close control is required, with a short lead near livestock at all times. No specific rule for the semi-feral Carneddau ponies is published. Treat them with the same livestock caution.

Routes & approach differences

The Ogwen Horseshoe is the shorter, more direct four-summit ridge from the A5 layby; the Craig yr Ysfa Circuit runs longer from Ogwen Cottage, adding a second scramble on the way down via Ffynnon Llugwy reservoir: not an easier alternative, just a different, longer day. No Eryri National Park route page exists for Carnedd Llewelyn; both routes here are inferred, assembled from independent walking-route guides, not an NPA-designated path. A third approach, from Gerlan (Bethesda) via Afon Llafar and Yr Elen, is confirmed to exist by two independent sources but its figures to Carnedd Llewelyn's own summit are not fully documented; it isn't given a full route card on this page.

Weather, visibility & winter conditions

Wind funnels hard on this ridge: a breeze that's manageable in the valley can be a real fight on the tops, and both routes hold long stretches of open, exposed walking. The summit plateau is flat and boulder-strewn with no obvious path, so cloud turns navigation into the day's real hazard, more than the scrambling. Snow or ice from November to April is common across the Carneddau. No official equipment mandate is published for Carnedd Llewelyn specifically, but an ice axe and crampons may be needed depending on conditions.

The Met Office publishes a location forecast named for this mountain (opens in a new tab) (listed in its gazetteer as Carnedd Llywelyn); MWIS (opens in a new tab) publishes a regional mountain forecast that names the Carneddau specifically within its Eryri/Snowdonia view. Read both, and read them as inputs rather than answers: a location forecast does not replace your own judgement about summit wind, cloud, visibility, snow and ice on a plateau with no path.

Descent planning & route mistakes

No alternative escape has been verified for either route; reversal is the confirmed plan on the Ogwen Horseshoe unless you continue on to Pen yr Helgi Du. On the Craig yr Ysfa Circuit, the second scramble comes on the way down, not just the way up. Treat descending it with the same seriousness as the climb, not as an easier formality at the end of a long day.

Emergency & what not to rely on

Dial 999 or 112 and ask for Police, then Mountain Rescue (emergencySMS also works if registered in advance). Ogwen Valley Mountain Rescue Organisation covers the Carneddau, Glyderau and Ogwen Valley. The T10 bus and Bws Ogwen shuttle run to a timetable, at the roadside; neither is a rescue or descent plan.

Accessibility & realistic limitations

Neither route is a short walk or a marked path; both are full, self-navigated mountain days with a scramble section, and neither is a first-mountain or family-friendly option. There are no facilities beyond the Ogwen start point, and no step-free or easy way onto the summit plateau.

Specific to this mountain

The Carneddau ponies & responsible visiting

The lower slopes are grazed by the Carneddau ponies, a genetically distinct semi-feral herd managed under a Natural Resources Wales agreement. Give them space. Wild camping isn't permitted anywhere in Eryri without the landowner's permission, and never in car parks or on verges.

The Avro Lincoln memorial, on the southern slopes

On the mountain's southern flank, wreckage and a granite tablet mark where an RAF Avro Lincoln (RF511) came down in bad weather in March 1950: six crew, none of whom made it home. It's off the summit itself and not something this photograph shows; three independent aviation-history sources agree on the date, unit and location.

Sourced from Eryri National Park Authority, Ogwen Valley Mountain Rescue Organisation, the Met Office and independent route guides, checked 17 July 2026.

The reckoning

Now: is today the day?

You've seen the two lines; the last question is the weather. The featureless summit plateau makes cloud a genuine hazard, not just a disappointment.

Carnedd Llewelyn forecast (opens in a new tab) MWIS regional forecast (opens in a new tab)

The Met Office link is a location forecast named for this mountain (listed as Carnedd Llywelyn); MWIS is a regional mountain forecast for Eryri/Snowdonia that names the Carneddau specifically. Read them together: a location forecast is not a substitute for judging summit wind, cloud, visibility, snow and ice yourself.

  • Location forecast, not a summit verdict

    The Met Office lists a location forecast for this mountain, and MWIS names the Carneddau specifically in its regional view. Neither is a summit-specific mountaineering forecast; on a plateau with no path, they inform the decision rather than make it.

  • Wind funnels on the ridges

    Both routes hold open, exposed ridge walking for much of their length; a valley breeze can be a fight on the tops.

  • The plateau whites out

    Independent sources agree the summit is a flat, boulder-strewn plateau; in cloud, finding the right line off it is the real hazard, not the climb.

Treat snow and ice as winter conditions. No official mandatory-equipment requirement is published for Carnedd Llewelyn specifically, but significant snow and ice are common across the Carneddau from November to April. Don't assume a route is in summer condition without checking first.

Good fit for

  • Hillwalkers ready for a full, self-navigated mountain day
  • Parties comfortable with a rocky scramble section and open-ridge exposure
  • Anyone wanting quiet, wide ridge walking away from the busiest routes

Think twice if

  • You want a short walk or a marked path; neither exists here
  • You're unsettled by scrambling or exposed ridge ground
  • You're not confident navigating a featureless summit plateau

The summit

What the climb gives back.

You climb for the top, but Carnedd Llewelyn's summit doesn't perform for the camera the way a sharp peak does; its reward is scale: a wide, quiet plateau, and the sense of standing on the Carneddau's highest ground.

The main summit cairn of Carnedd Llewelyn, on the broad stony plateau, with a hazy skyline beyond
Summit of Carnedd Llewelyn

The defining feature

A wide, flat plateau

A flat, boulder-strewn top marked by a single cairn. Carnedd Llewelyn doesn't perform for the camera the way a sharp peak does. The reward here is scale, not drama.

Weather permitting

The outlook

On a clear day, the high ground opens toward the Yr Wyddfa massif and, further off, the sea, though low cloud on the Carneddau is common enough that the view is a bonus, not a guarantee.

Why it matters

Featureless in cloud

The plateau's flatness is exactly what makes it a hazard in poor visibility: without a sharp summit cone to orient by, sound navigation matters here more than on almost any other Carneddau top.

The way down

Before you leave the summit.

Most of the day's trouble comes after the top, on a plateau with no obvious line to follow. Read the notices, then make the call.

Craig yr Ysfa, seen from Bwlch Eryl Farchog
Summit noticeboard
1

Navigation on the plateau

The summit is flat and boulder-strewn; the descent crosses the same featureless ground as the ascent.

  • Identify your descent line before you leave the top.
  • Carry a map and compass, and know how to use them.
Know the way down
2

The scramble is still there

Both routes' scramble ground — Pen yr Ole Wen, or Craig yr Ysfa — must be reversed or descended, not just climbed once.

  • Treat descending a scramble as seriously as climbing it.
  • Turn back rather than downclimb in doubt.
Turn back early
3

Changing mountain weather

An open ridge with no shelter: check the regional Eryri forecast before committing, and be ready to turn back.

  • Check the mountain forecast, not the valley one.
  • Keep a weather buffer for the descent.
Know your limits
4

Transport is not a descent plan

The T10 and Bws Ogwen run to a timetable, at the roadside. Not partway up the mountain.

  • Plan your own way down, on foot, in full.
  • Don't rely on a bus, signal, or luck.
Plan, don't rely

Back in the valley.

The Ogwen and Conwy valleys hold more than one mountain. These are the places around it.

Tryfan's rocky profile rising above the Ogwen Valley
Same valley

Tryfan

The Ogwen Valley's other summit, visible across the valley from the ridge: a real second mountain-day option, every route on it a scramble.

Read the guide →
Pen Llithrig y Wrach's flat-topped profile rising above the valley in the Carneddau
The same range, south

Pen Llithrig y Wrach

The Carneddau’s south-eastern outlier above Llyn Cowlyd: a shorter day on the same range, and usually an empty one.

Read the guide →
Llyn Crafnant, a forest lake above Trefriw
Conwy valley side

Llyn Crafnant & Geirionydd

Two forest lakes above Trefriw: flat, quiet ground for the evening after a long ridge day.

Read the guide →
Llyn Idwal's still water reflecting the cliff line of Cwm Idwal, Eryri
Across the Ogwen valley

Cwm Idwal

The glacial cwm on the far side of the A5: a lake circuit under the Devil’s Kitchen, and a much gentler way to spend the same weather.

Read the guide →

On the Atlas

Continue from Carnedd Llewelyn.

North of the Ogwen valley, near Bethesda and the A5.

Open Carnedd Llewelyn on the map

Continue exploring

The plateau falls away.Carnedd Llewelyn leaves the horizon wider.

Carry that sense of distance into the wider Carneddau.

Open Carnedd Llewelyn on the map Open Conwy Atlas