Arc of Attrition by UTMB 2027 – The Complete Race Guide & Tips

The name is not marketing. The Arc of Attrition by UTMB is exactly what it promises: a hundred-mile grind along the most exposed coastline in England, run in the dead of winter when Cornwall’s Atlantic-facing cliffs get hit with everything the ocean has. Rain, sleet, wind, mud that pulls at your quads with every step, and a course that does not relent from first kilometre to last. Between 40 and 50 percent of Arc 100M starters in most editions never reach the finish. In 2026, when Storm Ingrid arrived with the start gun, that number climbed to 59 percent.

For 2027, the Arc has a new finish venue: Perranporth Airfield on the north Cornwall coast, replacing the Eco Park at Porthtowan that served as race HQ for the previous decade. This is not just an administrative change. The Arc 100M now covers 173km with 5,507m of elevation gain — roughly 12km and several hundred additional metres of climbing added to a course that was already Britain’s toughest ultra. The cutoff has been extended by one hour to 37 hours to account for the extra distance, but this is a harder race than the one that turned back nearly two-thirds of its field in 2026.

There are four distances in 2027. The Arc 100M starts from Coverack on the south coast at 13:00 on Friday 22 January, following the arc of Cornwall’s coastline around Land’s End and up the wild western peninsula to Perranporth Airfield. The Arc 100K starts from Land’s End on Saturday morning. The Arc 50K starts from Harlyn Bay and the Arc 20K from Perranporth Airfield, both on Sunday. All races are UTMB World Series events: finishers earn Running Stones toward the UTMB Mont Blanc ballot and Arc 100M podium runners earn direct entry to UTMB in Chamonix.

This guide is built primarily around the Arc 100M. It is the race that defines this event’s reputation and the one most people travel to Cornwall to attempt. If you are considering the shorter distances, the course and strategy sections translate broadly, but the detailed segment analysis below focuses on the full hundred. Be aware that the 2027 course extension beyond Porthtowan is new — no previous race report covers it, and we treat that honestly in the course section.

Arc of Attrition by UTMB 2027 — Race at a Glance

Arc of Attrition 2027 — Registration and Entry

Registration for the 2027 edition is open. There is no lottery and no ballot. UTMB Index holders received a 48-hour priority window from 13 July 2026; general registration opened on 15 July 2026. The Arc 100M in particular does not have unlimited spots, and a field that routinely sees more than half its starters DNF does not stop the race from selling out. If you are reading this and registration is still live, do not sit on it.

Who Can Enter

2027 Entry Fees

Exact 2027 tiered pricing was not publicly listed at the time of writing this guide. Based on 2026 edition pricing, the Arc 100M ranged from approximately £209 at early entry to £259 at late entry. The Arc 50K ranged from approximately £139 to £189. With the 2027 course extended by 12km, fees for the 100M may be slightly higher. Always confirm current pricing on the official registration platform before making plans.

Register for Arc of Attrition 2027 on the official UTMB platform

What Makes the Arc of Attrition Worth Running?

The Most Honest Buckle in British Ultrarunning

There are races where finishing is an achievement. The Arc of Attrition is that race multiplied by a factor most runners underestimate until they are standing in the Zennor boulder field at 4am with 30km still to run. The average DNF rate across all Arc 100M editions is roughly 50 percent. In bad weather years it climbs higher. The sub-24-hour Black Buckle, the sub-30-hour Gold and the sub-37-hour Silver all carry real weight precisely because they are genuinely difficult to earn. Nobody flukes a finish here.

A Direct Route into the UTMB World Series

Since joining the UTMB World Series, the Arc has become a significant points-earning event on the global ultra calendar. Finishers earn Running Stones toward the UTMB Mont Blanc ballot — the lottery entry system for the world’s most famous trail race. The top three male and female finishers in the Arc 100M earn direct entry to UTMB Mont Blanc in Chamonix. Arc 100K podium runners earn direct CCC entry; Arc 50K podium earns OCC. For any runner building toward the Chamonix finish line, the Arc is now an important step on that path.

A Course That Tests Who You Are at 3am

Cornwall’s South West Coast Path in summer is a beautiful walking trail. In January, in a headtorch, in a howling Atlantic storm, it is something entirely different. The cliff tops are narrow. The boulders at Zennor are boulder-hopping terrain, not running. The sea is audible the entire way. Long stretches between aid stations force genuine self-sufficiency. This race tests who you are when conditions get brutal and the exit options disappear.

It Suits the Experienced — Not the Ambitious Beginner

The Arc organisers say it plainly in their own FAQ: do a gentler 100-mile race first, something like a Centurion event, before attempting the Arc. The mandatory kit list is extensive and the kit check is thorough — arrive without every item and you will not start. The race is built for runners who have been moving in the dark for 20 hours and know exactly how their bodies and minds respond. The Arc 50K or Arc 20K are far better entry points for anyone new to ultra distances on this terrain.

Cornwall in January — Wild, Remote and Unforgettable

Even in the worst conditions the Arc course is extraordinary. The Lizard Peninsula at dusk, Land’s End at 3am, the St Ives skyline at sunrise after a sleepless night on the trail — these are moments that stay with runners long after the finisher buckle collects dust. The 2027 course adds new ground north of Porthtowan on the approach to Perranporth, cliff paths and coves that no previous Arc runner has ever raced. In good conditions that extension will be spectacular. In a storm it will be earned.

The 2027 Course Is Genuinely New

The shift to Perranporth Airfield as the finish venue makes the 2027 Arc 100M a different race from everything that has gone before. Twelve additional kilometres at the end of 100-plus miles. New terrain that no Arc runner has raced on. A finish area that is more accessible and more sheltered than the old Porthtowan site. For experienced Arc runners, this changes every pacing and crewing conversation they have had about the back section. For first-timers, it means the final segment of this guide — and of every other course guide written before 2027 — carries an honest uncertainty that we address directly in the course section below.

The Arc 100M Course — Section by Section

Section 1: Coverack to Cadgwith (km 0–15)

The race starts at 13:00 from the village of Coverack with an immediate bottleneck on a narrow, gorse-lined path that makes overtaking nearly impossible for the first kilometre. Elites and enthusiastic mid-packers compress into a single-file queue. It is slower than you want and exactly as slow as you need. This is genuinely runnable coast path with rolling terrain and good footing. You are in full afternoon daylight, likely in a pack, feeling better than anyone running 173km has any right to feel. Treat that feeling with suspicion. Every Arc 100M finisher reports running this section slower than training pace. Every one of them says it was the right call.

Section 2: Cadgwith to Lizard Point to Kynance Cove (km 15–26)

The path gets narrower and more committing as you move toward the Lizard Peninsula, the southernmost point of mainland Britain. Late afternoon light on these cliffs is as good as Cornwall gets. The path sits close to the edge; concentrated footwork is needed at exposed corners, especially if the ground is wet. The first aid station at Kynance Cove arrives at approximately km 22. Eat something light and move on. Food choices that feel fine at km 22 sit badly in the stomach when you are boulder-hopping in the dark at km 120.

Section 3: Kynance Cove to Porthleven (km 26–45)

A long transitional section that starts easy and gradually tightens. Daylight drops somewhere around km 35–38, depending on cloud cover. Head torches on before you need them. The six kilometres from Mullion to Porthleven at night, on legs that have already covered a marathon, is where the Arc first introduces itself properly. The distance feels longer than the map says. This is not an illusion — fatigue, darkness and cold compound perceived effort against actual distance. Porthleven is the first major aid station, at approximately km 45.

Section 4: Porthleven to Penzance (km 45–64)

The beach section. Easier underfoot across Prussia Cove, Marazion and into the outskirts of Penzance. This is the last sustained stretch of genuinely fast terrain on the entire course. The major aid station at Penzance sits at approximately km 64. Sit down. Change your socks. Eat a proper meal. Do not panic about the time. Ten to fifteen minutes at Penzance is not lost time — it is the difference between walking and crawling through what comes next.

Section 5: Penzance to Lamorna to Porthcurno (km 64–80)

This is where the course changes character and does not revert. Granite approaches, steep cove climbs and technical footwork replace the runnable coast path of the early sections. Expect your pace to drop 30–40 percent compared to the first 60km. This is normal and it is correct. The climb out of Lamorna at approximately km 72 is the point where the highest proportion of recreational runners consider stopping. It is a hard climb on already tired legs. It is not, however, the hardest thing on this course — not even close. Push through. The section after Lamorna rewards the runners who kept moving.

Section 6: Porthcurno to Land’s End to Sennen (km 80–93)

Land’s End marks a psychological waypoint. In terms of distance it sits roughly at the halfway point; in terms of time it absolutely does not — the back half of the Arc is significantly slower per kilometre than the first. Most runners arrive at Land’s End somewhere between 2am and 5am. The iconic milestone of the tourist season looks very different at 3am in a January headtorch beam. If you are ahead of schedule, pause briefly. If you are behind cut-off pacing, walk through and keep moving.

Section 7: Sennen to St Just to Cape Cornwall to Pendeen (km 93–113)

The hardest sustained section in terms of weather exposure, before the Zennor stretch. This is exposed Atlantic headland running at 4–6am in January. If wind has built since the race start — and in most editions it has — the windchill at Cape Cornwall and the approach to Pendeen can be genuinely dangerous without proper layering. Two pairs of gloves, a mountain-grade waterproof and something over the face are not paranoia here; they are what stands between you and hypothermia. There is no road access through most of this section. The aid station at Pendeen, at approximately km 113, is the last resupply before the hardest kilometres on the course. Take every calorie on offer.

Section 8: Pendeen to Zennor to St Ives (km 113–132)

This is where Arc 100M races are won and lost. The Zennor boulder field — approximately 20km of granite slab hopping, technical foot placement and ankle-threatening terrain — is the most demanding section on the entire South West Coast Path. At km 113, on legs that have covered the equivalent of a hundred miles in the dark, it is not runnable. Elite runners do not run it. Attempting to move at running pace when you should be walking with purpose is the leading cause of race-ending falls and ankle injuries in this section. Take every step deliberately. Poles are worth every gram of weight here. St Ives arrives at approximately km 132. If your timing is right, you will see it at dawn. That sunrise has helped hundreds of Arc runners get moving again after the worst night of their running lives. Take thirty seconds. Then keep moving.

Section 9: St Ives to Hayle to Gwithian (km 132–148)

After Zennor, flat estuary miles along Hayle feel close to miraculous. Runners who have been boulder-hopping for two-plus hours suddenly find firm ground and recoverable pace. This is a genuine recovery section. The Hayle estuary crossing and the dunes at Gwithian are kind to tired legs. By km 148 you have covered roughly 92 miles of the old Arc 100M course. The new race, however, continues.

Section 10: Gwithian to Portreath to Porthtowan to Perranporth Airfield (km 148–173)

Previous editions of the Arc 100M finished at Porthtowan’s Eco Park. In 2027, the course continues approximately 12km further north along the South West Coast Path to Perranporth Airfield. This is new race territory.

Arc of Attrition Race Strategy

Arc of Attrition 2027 — Race Weekend Schedule

The schedule below is confirmed from the official event calendar but is subject to change. All TBC timings will be confirmed in the Runner’s Guide issued before the end of 2026. All times are GMT.

Arc of Attrition Weather — What January in Cornwall Actually Means

Cornwall’s position on the Atlantic coast means conditions change faster and more severely than standard UK weather forecasts suggest. The organisers will issue a weather briefing in the Runner’s Guide and communicate any changes to mandatory kit requirements in the 24 hours before each race start. Do not make kit decisions based on a forecast you checked at home two days before the race. The Cape Cornwall headlands and the Pendeen-to-Zennor section can hold localised storm conditions that do not appear on regional forecasts. Carry the full mandatory kit regardless of how mild it looks in Perranporth on Friday morning.

Past Results — Arc of Attrition 100M Defending Champions

Arc of Attrition Spectator Guide

Watching the Arc is an event in itself. The course is point-to-point and follows cliff tops with no road access for long stretches. With planning, crew and supporters can intercept runners at several key locations. The new finish at Perranporth Airfield — more accessible and more sheltered than the old Porthtowan site — makes the finish line experience considerably better for everyone not running.

Where to Stay for Arc of Attrition Race Weekend

The 2027 race footprint spans from Coverack in the southeast to Perranporth Airfield in the northwest. The practical approach is to base yourself within 30–45 minutes of Perranporth, use the event coaches to the Arc 100M and Arc 100K start lines, and avoid the trap of chasing accommodation at each separate start location across Cornwall.

International Runners — Visa and Getting to Arc of Attrition

Getting to Cornwall

Cornwall is the most remote point in England from most major airports and from London. Building this into travel planning early is not optional — race weekend logistics begin long before you reach Perranporth Airfield.

Visa Requirements for the UK

A Short History of the Arc of Attrition

The Arc of Attrition started in January 2015 with 54 runners and a clear brief: fill a gap in the UK winter ultra calendar with something genuinely hard. MudCrew, the Cornwall-based organisation that created the event, laid the course along the South West Coast Path from Coverack to Porthtowan — a natural arc around the extreme southwestern tip of England. The first edition had no fanfare and minimal infrastructure. Duncan Oakes won in 22:48:43 and Charlie Ramsdale took the women’s race. The field was small, the race was hard and word spread.

The event’s reputation as Britain’s toughest ultra was forged across the following years through a combination of brutal weather and a DNF rate that made no apologies. The 2016 edition remains the most extreme in Arc history: only 28 runners finished from a field of roughly 110 starters, with storm-force winds and continuous rain holding the completion rate below 25 percent. MudCrew kept the bar where it was. The race grew precisely because it refused to get easier. By the early 2020s the Arc had expanded to multiple distances and a multi-thousand runner field drawing international elites. Emma Stuart shattered the women’s course record in 2023 by nearly four hours. Mark Darbyshire became the first man under 19 hours in 2024.

In 2025 the Arc joined the UTMB World Series — connecting it to the global elite trail calendar, bringing live GPS tracking, UTMB Running Stones and a new level of international field depth to the Cornish coast. None of that changed the weather and none of it changed the course. For 2027, the event moves its finish to Perranporth Airfield and extends the Arc 100M to 173km, the most ambitious race format in the event’s twelve-year history. The cliff tops have not changed. January has not changed. The Arc is still the same fight it always was.

How Arc of Attrition Compares to Other Major Ultras