Marathons in Wales

From the Newport Wales Marathon, one of Europe's flattest PB courses, to the savage mountain climb of Eryri (Snowdonia) — Welsh racing runs the full spectrum. Pick your battle below.

Updated 2026-07-13 Sorted by race date. Field sizes and course data are checked against each race's official source.

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About marathons in Wales

Two extremes, one country. Welsh marathoning runs from the pancake-flat Newport Wales Marathon (mid-April, about 4,000 runners, roughly 26 m of total climb), one of Europe's fastest PB courses, to the savage mountain loop of Eryri (Snowdonia, late October, about 840 m of ascent), with the Long Course Weekend in Tenby (late June), the clifftop Gower Marathon (early November) and the Great Welsh Marathon at Llanelli (October) in between. Cool, damp, breezy Atlantic weather is the constant — rarely hot, almost always green.

Choosing one. Are you chasing a time or an experience? For the clock, Newport and the rolling Great Welsh are the only two BQ-eligible courses here — check your target with the Boston Qualifying calculator and the UK PB guide. The southern races (Newport, Gower, Tenby) are reachable by the M4 and mainline rail, while Eryri sits deep in the north-west, runs by ballot, and needs planning months ahead. See the best-of Wales guide for the full shortlist, and pack for wind and rain even in summer.

Frequently Asked Questions

Which marathon in Wales is best for a personal best?

The Newport Wales Marathon in April is the clear pick. Its flat riverfront course (roughly 26 m of total climb), drawn up by double Olympic marathoner Steve Brace, is regularly named among the fastest in Europe and has appeared on Runner's World's list of the fastest marathons in the world. Newport reports that nearly 70% of finishers set a personal best on it, and the flat profile plus a roughly 4,000-runner field make it ideal if your goal is a fast time. It is also Boston-qualifier eligible.

What is the hardest marathon in Wales?

That title belongs to Eryri Marathon (the Snowdonia Marathon), run from Llanberis in late October. The course climbs the Llanberis Pass and loops around Yr Wyddfa, the highest mountain in Wales, with roughly 840 m of ascent and exposed mountain weather. It is billed as one of the toughest road marathons in the UK and the opposite of a PB course.

When is the marathon season in Wales?

It spans spring and autumn. Newport opens the year in mid-April, the Long Course Weekend Wales at Tenby lands in late June, and autumn is busiest of all: the Great Welsh Marathon at Llanelli in mid-October, Eryri in late October, and the clifftop Gower Marathon in early November. Several events use ballots, so enter early.

What is the biggest marathon in Wales?

The Newport Wales Marathon is the largest, with a field of around 4,000 runners. Eryri (Snowdonia) is next at about 2,800, capped by its mountain logistics. The Gower, Tenby and Great Welsh races are smaller, more boutique events — part of their appeal, but they sell out or fill their ballots quickly.

Which Wales marathon is best for a first-timer or beginner?

Stick to the flat, well-supported south. Newport is the easiest underfoot — flat, city-centre and generously organised — making it the friendliest debut. The Great Welsh Marathon at Llanelli is another gentle, rolling option (about 110 m of climb). Avoid Eryri and Gower for a first marathon: both carry serious elevation and exposed weather.

How do you enter the popular Wales marathons — ballot or open registration?

It depends on the race. Eryri (Snowdonia) fills by ballot — it is heavily oversubscribed each year, with a short December entry window and charity places as a backup — so plan months ahead. Newport, the Great Welsh, Gower and the Tenby Long Course Weekend are open-entry and first-come, but the smaller fields can still sell out, so book early.