300-mile ultra marathon across Wales opens for sign-ups

A brand new ultra marathon from Conwy to Cardiff “designed to celebrate Wales and the Cambrian Way” has opened for sign-ups.

Any race that extends beyond the standard marathon length of 26.2 miles is classed as an ultra marathon, but the new offering from Stable Adventures will push the limits, covering 300 miles.

The Calon Lân 300 will be held from 5 to 12 July 2027, and includes 74,000ft of elevation through Eryri National Park, mid Wales, and Bannau Brycheiniog National Park.

Stable Adventures have hosted several ultra races across Wales over the last decade, usually following established routes like the Wales Coastal Path and the Epynt Way.

The Calon Lân will be one of their longest, beginning in Conwy and travelling coast to coast along the Cambrian Way to Cardiff over seven and a half days at the height of summer.

The Cambrian Way website describes the route as “Wales’ most scenically beautiful and challenging long distance trail”.

Though parts of the route pass through towns on paved roads, much of the terrain is rugged, and walkers are typically advised to take around three weeks to complete it.

 

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Calon Lân organisers explained: “From wild moorlands and rocky ridgelines to quiet valleys, ancient forests, and sweeping high passes, the Cambrian Way serves up some of the most spectacular terrain Wales has to offer.

“The route constantly shifts in character, keeping things fresh and engaging – whether you’re grinding up a steady climb, cruising along a runnable stretch, or pausing for a moment to take in those endless Welsh views.”

Announcing the opening of sign-ups at midnight on Saturday, 21 March 2026, the organisers called the race “a true adventure”, and reminded those interested that it would not be an easy undertaking.

However, they clarified that though the event is non-stop, it will be “incredibly doable when taken step by step”, and is “fully supported, with food and drink at aid stations, sleep stations, a skilled medical team, and live tracking so friends and family can follow your journey.”

The 11 checkpoints will be stocked with food and drinks, and manned by volunteers. To make the adventure “seriously achievable” organisers have also worked in generous cut-off times for reaching 100 (55 hours), 200 (115 hours) and 300 (180 hours) miles.

Runners will also receive a series of emails to help with preparation, as well as a phone call from the Race Director to ensure they are ready for the run.

Those who finish will earn a finisher buckle, a collectable medal and map, and a finisher jacket, as well as the satisfaction of knowing they completed one of the country’s longest ultra marathons.

Those interested can find more information and the sign-up link on the Calon Lân 300 site. The entry fee is £799, with only 150 places available on a first-come, first-served basis.