United Kingdom · England
Distance
161 km
Date
Entry fee
299
€ / km
€1.85
Arc of Attrition Arc100 (161.2km): Cornwall's January 100-Miler, Measured
Arc of Attrition by UTMB – Arc100 is a 161.2 km coastal trail race held each January in Cornwall, England, running point-to-point from Coverack to Porthtowan along the South West Coast Path. The 2027 edition is expected in January 2027. The course gains 5,300 m (32.9 m/km) — note: official site states 4,010m; — across cliff paths, beach crossings, and headland traverses, with 47.9% of the course flat or rolling. The defining factor is weather, not gradient. Cornwall in January brings Atlantic storms, ankle-deep mud, and cliff-top wind chill for 24–36 hours.
The 2026 edition brought Storm Ingrid (50mph winds) — only 40% finished. The 2025 edition ran post-storm with a 74% finish rate. The average historical DNF rate exceeds 50%. Entry requires prior completion of a 100km race and significant night-running experience. Registration fees for 2027 are not yet available. The 2025 edition drew 252 finishers at the 161km distance. Course records: 18:51:54 (men, Darbyshire) and 21:22:16 (women, Stuart). It suits highly experienced trail runners prepared to race winter coastal exposure at the UTMB World Series level — this is not a first 100-miler.
Elevation and Terrain
Total Meters
5,300m
D+/KM
32.9m/km
For context, the Tor des Géants 330 loop has 73 D+/km.
Avg Uphill Gradient
8.7%
Avg Downhill Gradient
-8.2%
Uphill gradient distribution
| 2–5% | 15.9 km | |
|---|---|---|
| 5–10% | 13.1 km | |
| 10–15% | 7.1 km | |
| 15–20% | 2.6 km | |
| 20%+ | 3.0 km |
Route Profile
AnalysedTerrain breakdown
| 25.7% | Uphill |
|---|---|
| 47.9% | Flat |
| 26.4% | Downhill |
Terrain
Arc of Attrition by UTMB – 161.2 km 161km Top Climbs
Top Climbs
| 1 | 1.2 km · 88 m gain starts km 160 · avg 7.4% · max 26.0% |
|---|---|
| 2 | 0.5 km · 82 m gain starts km 106 · avg 15.2% · max 33.8% |
| 3 | 0.8 km · 74 m gain starts km 96 · avg 9.9% · max 28.6% |
Top descents
| 1 | 1.6 km · 79 m drop starts km 109 · avg -4.9% · max -26.0% |
|---|---|
| 2 | 3.6 km · 71 m drop starts km 121 · avg -2.0% · max -25.9% |
| 3 | 2.3 km · 67 m drop starts km 101 · avg -3.0% · max -12.0% |
High DNF Rates and Coastal Attrition: The Arc of Attrition by UTMB 161.2km Difficulty Profile
How hard is the Arc of Attrition Arc100 (161.2km)?
▼
One of the most attrition-heavy 100-milers in Europe — average DNF rate exceeds 50% historically. The difficulty is not gradient (47.9% of course is flat) but exposure: 24–36 hours of Atlantic winter conditions on the South West Coast Path, with ankle-deep mud, cliff-top wind chill, and the Botallack-to-St-Ives section at km 95–120 described as '15 miles of pure grind.' The race officially states 'the primary challenge is the weather rather than the land.'
UTMB World Series 100M and Running Stones: Arc of Attrition by UTMB Arc100 Race Credentials
Is the Arc100 a UTMB qualifier?
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Yes — UTMB World Series 100M category with running stones awarded. The Arc of Attrition joined the UTMB World Series in 2025, building on its MudCrew origins since 2015. ITRA points are also awarded — confirm current values before entering.
Entry Requirements for the Arc of Attrition by UTMB 161.2 km: Experience, Age, and Prior Race Credentials
What are the entry requirements for the Arc100?
▼
You must be over 21, have completed at least one 100km trail or ultra race, and have considerable night-running experience. These prerequisites are enforced — the Arc100 is not a first ultra.
Entry Fee and Registration Timeline for Arc of Attrition Arc100 (161.2km)
How much does the Arc100 cost to enter?
▼
Entry fees for the 2027 edition are not yet published. The 2026 edition has passed. Check arcofattrition.utmb.world from approximately March 2027 for 2027 pricing.
Who Should Run the Arc of Attrition Arc100?
Who Should Run the Arc of Attrition Arc100?▼
Newquay Airport (NQY) is the primary option, approximately 20–60 minutes from St Ives. Exeter (EXT) is 2–3 hours; Bristol (BRS) is ~3.5–4.5 hours — effectively FAR. Good rail from London Paddington via St Erth to St Ives. The race is point-to-point (finish in Porthtowan); return transport needs planning. January accommodation in St Ives is very limited — book immediately when registration opens.
Arc of Attrition by UTMB – 161.2 km 161km GPX
Getting to Arc of Attrition by UTMB – 161.2 km
Nearest airport
Newquay (NQY) / Exeter (EXT) / Bristol (BRS)
Notes
Start: ~20–60 min (NQY) or ~2–3 hrs (EXT) or FAR - ~3.5–4.5 hrs (BRS) to St Ives / Cornwall / Public transport: good rail to St Ives (via St Erth); point-to-point finish logistics often need car or event transport / Accommodation: very limited in St Ives in winter; book early; nearby towns work
