How far is the Sea to Summit Yr Wyddfa?

The Sea to Summit Yr Wyddfa is one distance: 47km (29.2 miles).

Is the Sea to Summit Yr Wyddfa course marked?

Yes, the course is marked. Navigation skills are not required.

Rat Race Sea to Summit Yr Wyddfa

Caernarfon Castle, GwyneddSat, 26 Sept 2026

Forty-seven kilometres from the gates of Caernarfon Castle to the summit of Yr Wyddfa.

47km

29 miles

mountainMarked course

Nobody has reviewed this one yet

No reviews of the Sea to Summit Yr Wyddfa, and nothing on what people wore. Both are things no organiser publishes and every runner wants before they enter — how it actually went, and what was on your feet.

Ran it? Write the first review

Running it soon? Connect Strava and we will ask you about it the day you finish, so you do not have to remember to come back.

The course

Start time not confirmed yet — check with the organiser.

What you’re in for

Forty-seven kilometres from the gates of Caernarfon Castle at sea level to the summit of Yr Wyddfa — the highest point in Wales — on a marked course. Late September.

Terrain and trail

Lane, cycle path and lakeside trail out of Caernarfon, then the mountain: a long, stone-pitched climb to the summit with the exposure and weather that go with 1,085m. Marked, but carry mountain kit; the top is a different day from the bottom. A trail shoe with grip.

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Train for it: routes near the start

Routes starting within 20 km of Caernarfon Castle, Gwynedd, nearest first. Each one has a free GPX file and a TRP grade, so you can rehearse the ground before race day.

VERY HARD

Yr Wyddfa via Llanberis Path

16.2km · 959m climb · Out & back · 10km away

It's the most runnable line to the summit of Yr Wyddfa, following the rack railway most of the way up, so you can move fast on genuinely good underfoot conditions rather than picking through rock.

EXPERT

Snowdon, Grib Goch, Glyder Fawr, Y Garn & Elidir Fawr from Llanberis Trail Running Route

29.1km · 2,306m climb · Loop · 10km away

Crib Goch is one of the most exposed ridges in Britain, and this route puts it in the middle of a big mountain day rather than as the whole objective, so you get the scramble and a proper crossing into the Glyderau either side of it.

Checked Jul 2026

EXPERT

Yr Wyddfa via Miners' Track, Pyg Track and Crib Goch

12.0km · 710m climb · Loop · 18km away

Most people treat the Miners' and Pyg Tracks as a straightforward there-and-back pairing, but this GPX shows the loop actually crossing Crib Goch, which changes the entire character of the day.

All Eryri (Snowdonia) routes →

How to enter

Sat, 26 Sept 2026 · Event full

See the event on their website ↗

Entries are handled by Rat Race, not by us. We take nothing for sending you there.

Add to your calendar · as an all-day entry, until the start time is confirmed

Common questions

: The Sea to Summit Yr Wyddfa is one distance: 47km (29.2 miles).
: No course file for the Sea to Summit Yr Wyddfa yet, so there's no measured climb here. When Rat Race publish one, this fills in.
: Not graded yet. A TRP grade is worked out from distance and climb measured off the course file, and there isn't one for the Sea to Summit Yr Wyddfa yet.
: Yes, the course is marked. Navigation skills are not required.
: We don't hold a compulsory kit list for the Sea to Summit Yr Wyddfa. Rat Race confirm mandatory kit in their race information, usually in the final instructions.
: We don't hold published time limits for the Sea to Summit Yr Wyddfa. If Rat Race set cut-offs, they'll be in the race information.
: We don't hold a checkpoint list for the Sea to Summit Yr Wyddfa. What's on the table varies a lot between races, so check the Rat Race race information rather than turning up expecting food.
: Not yet — we don't hold a course file for the Sea to Summit Yr Wyddfa. Some organisers only send the GPX to entrants. If we get one, it goes up free, with no sign-up.
: Sat, 26 Sept 2026. Event full.