Marathon Eryri Course Guide 

Marathon Eryri Course Guide

Where to Settle Where to Focus and When to Fuel

This is how Marathon Eryri usually feels on the day rather than how it looks on the elevation profile.

Pre Start Twenty Minutes to Go

Llanberis

The race starts at 10.30am just outside Llanberis, but the morning can involve plenty of waiting around in the village.

Many runners have eaten breakfast quite early due to travel and accommodation logistics.

By twenty minutes to go it is common to feel nervous. This race carries a reputation, and that alone can tighten breathing or upset the stomach.

Many experienced Eryri runners take a Sport Jelly around twenty minutes before the start. It requires no water and provides readily available fuel just as the race begins.

Use this time to slow your breathing, relax your shoulders and remind yourself that today is about managing effort, not impressing anyone early.

If it feels cold standing still, that is normal. Use discardable layers rather than trying to warm up aggressively.

First timers should frame this as a long journey through the mountains, not a race against the clock.

Miles One to Six

Llanberis to Pen y Pass
The First Major Climb

The race heads out of Llanberis along the A4086, immediately beginning the long climb through the Llanberis Passtowards Pen y Pass, topping out at around 1,100 feet.

This climb is steady, scenic and relentless.

Snowdon (Yr Wyddfa) dominates the skyline and it is easy to be distracted by the scenery — but this is not the place to push.

Effort matters more than pace here. Running too hard early almost always shows later.

Many experienced runners fuel early on this climb, taking a Sport Jelly or sipping Energy Fuel if carrying fluid.

Mentally, accept the climb. Fighting it wastes energy.

Miles Seven to Ten

Pen y Pass to Pen y Cwyryd and the Old Road

After cresting Pen y Pass, the course drops down towards the Pen y Cwyryd junction before turning onto the old road.

This section includes around 2km of farm track, downhill in places, before returning to tarmac.

The change in surface can catch runners out. Stay controlled, especially on tired legs, and watch footing if conditions are wet.

There is a short, sharp climb back up to the main road near the campsite. It is brief but punchy.

Keep fuelling here. The downhill can mask effort, but energy is still being used.

Miles Eleven to Fifteen

Beddgelert
False Comfort

The route joins the A498 and continues towards Beddgelert, dropping to around 200 feet.

This section often feels deceptively runnable.

The village of Beddgelert brings strong support and a brief psychological lift. Many runners feel tempted to make up time here.

Resist the urge to push. This race still has plenty to take from you.

This is an ideal window to lock into a fuelling routine. Many runners aim for forty to eighty grams of carbohydrate per hour depending on experience and goals.

Keep fuelling. Consistency matters more than exact timing.
Early fuelling here helps prevent later energy dips and avoids having to play catch up.

Miles Sixteen to Eighteen

Along the A4085
Settling In

Leaving Beddgelert, the course follows the A4085 towards Waunfawr.

This is where the race starts to feel honest.

The excitement has faded, fatigue is present and the next major climb looms.

Runners who have fuelled consistently usually feel steady here. Those who have not often start to feel flat without a clear reason.

Use this section to reset. Breathing. Posture. Fuelling.

Miles Nineteen to Twenty Three

Waunfawr to Bwlch y Groes
The Defining Climb

From Waunfawr, the route turns skyward again with a rapid climb to around 1,200 feet at Bwlch y Groes.

A short section here is unmetalled, adding to the challenge.

Pace will drop significantly. That is expected.

Shorten your stride. Stay tall. Keep moving forward efficiently. Walk briefly if needed rather than forcing poor form.

Fuelling here matters more than pace. Continue to take carbohydrate even if speed is low.

Mentally, this is the heart of the race. Stay composed and patient.

Miles Twenty Four to the Finish

The Descent Back to Llanberis

The final descent into Llanberis is fast, steep and in places down a rough track.

Tired quads are vulnerable here. Stay controlled and avoid reckless descending.

As you re-enter Llanberis, crowd support builds and carries you towards the finish.

If you have managed pacing and fuelling well, you will still be able to run strongly and soak up the atmosphere.

The finish in Llanberis is emotional, loud and deeply satisfying.

View our Marathon Eryri Race Day Tips or if you’d like a deeper dive into fuelling strategies, carb targets and pacing guidance, you can read the full Mountain Fuel Road Marathon Nutrition Guide