How far is the Snowdonia Sea2Sky?

The Snowdonia Sea2Sky offers 3 distances: 53K (32.9 miles), 25K (15.5 miles), 12K (7.5 miles).

How much climbing is in the Snowdonia Sea2Sky?

The 53K has 1,647 m of ascent. The 25K has 739 m of ascent. The 12K has 600 m of ascent.

What are the cut-offs for the Snowdonia Sea2Sky?

Overall time limits — 53K: 11h, 12K: 4h.

When is the next Snowdonia Sea2Sky?

Sat, 5 Sept 2026, 08:00. Entries open.

Barmouth, Gwynedd

RunThrough Trails Snowdonia Sea2Sky

Sat, 5 Sept 2026

From the beach at Barmouth into the Eryri mountains.

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What runners wore

Nobody has told us what they wore on the Snowdonia Sea2Sky yet. It is the thing most runners want to know before they enter, and no organiser publishes it.

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Pick your distance

53.0

km · 32.9 mi

1,647

m ascent

6 checkpoints · 11h cut-off · start time 08:00

Terrain and trail

mountaincoastal

Reviews

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How to enter

Sat, 5 Sept 2026 · Entries open

No entry link yet. Check RunThrough Trails’s site ↗

Common questions

: The Snowdonia Sea2Sky offers 3 distances: 53K (32.9 miles), 25K (15.5 miles), 12K (7.5 miles).
: The 53K has 1,647 m of ascent. The 25K has 739 m of ascent. The 12K has 600 m of ascent.
: 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 Snowdonia Sea2Sky yet.
: We haven't confirmed the marking on the Snowdonia Sea2Sky with RunThrough Trails. Check their race information before you enter rather than assuming it either way.
: We don't hold a compulsory kit list for the Snowdonia Sea2Sky. RunThrough Trails confirm mandatory kit in their race information, usually in the final instructions.
: Overall time limits — 53K: 11h, 12K: 4h.
: We don't hold a checkpoint list for the Snowdonia Sea2Sky. What's on the table varies a lot between races, so check the RunThrough Trails race information rather than turning up expecting food.
: Not yet — we don't hold a course file for the Snowdonia Sea2Sky. Some organisers only send the GPX to entrants. If we get one, it goes up free, with no sign-up.
: Sat, 5 Sept 2026, 08:00. Entries open.