Arc of Attrition by UTMB (UTMB World Series)
Arc 100 – Arc of Attrition by UTMB
Coverack → Porthtowan
Race guide
Updated 29 June 2026
The Arc of Attrition is a 161 km coastal ultra running the full southwestern tip of Cornwall from Coverack to Porthtowan, entirely on the South West Coast Path. With only 2655 m of total ascent and a high point of just 114 m, it is not a mountain race — yet its finishing rate is brutally low. The terrain is relentlessly technical: rocky coves, exposed headlands, muddy cliff paths and hundreds of short, sharp rollers that grind legs down far more efficiently than any sustained alpine climb. Add January conditions — Atlantic storms, salt spray, darkness, cold and wet — and you have one of the most attrition-heavy events in European ultrarunning. The race is a UTMB World Series qualifier, starting at Coverack on the Lizard Peninsula and finishing at Porthtowan Eco Park with a Sunday 01:00 cut-off.
Course & Terrain
The route follows the South West Coast Path almost in its entirety, threading through some of the most dramatic and technically demanding coastal scenery in Britain. From Coverack the path tracks south to the Lizard checkpoint at 18 km — the most southerly point on mainland Britain — before turning north through Porthleven (40 km) and Penzance (61 km). The halfway anchor is Land's End / Sennen at 90 km, after which the course pushes up the more rugged north Cornish coast through Pendeen (103 km), St Ives (124 km) and Godrevy / Hayle (140 km) before the final push to Porthtowan. Despite the modest elevation profile, the path is almost never flat: expect constant ankle-testing descents into coves and steep, rooty pulls back out, interspersed with exposed cliff-top ridges. The low maximum elevation of 114 m is misleading — the accumulated mechanical stress of hundreds of these micro-climbs across 161 km of often boggy, rocky path is what defines the race.
The Decisive Sections — Where the Race Is Won or Lost
The stretch from Land's End / Sennen (90 km) through Pendeen (103 km) and up to St Ives (124 km) is where the Arc is truly decided. The north Cornish coast is rougher, more exposed and more technical than the southern leg, and it arrives precisely when most runners have already absorbed a full night of effort. Rocky headlands, cliff-edge scrambles and narrow, uneven path demand full attention from legs that have been running for 16–20+ hours. The section from St Ives to Godrevy / Hayle (140 km) crosses a mix of beach, estuary and exposed coastal path and can feel deceptively approachable on a map — in reality it is where many runners' rhythms finally break. The final 21 km from Godrevy to Porthtowan carries the accumulated weight of everything before it, and the modest climb to the finish at Porthtowan Eco Park (100 m) arrives as a sting in the tail.
Pacing Strategy — The Deposit-and-Spend Model
The Arc rewards one pacing philosophy above all others: go genuinely easy in the first half and spend the savings in the second. The southern leg to Land's End (90 km) can feel free and flowing — comfortable pace, social running, good spirits — and that feeling is exactly the trap. Runners who respond to that ease by pushing will pay compound interest on the north Cornish coast after sunrise. The proven approach is to treat the first 90 km as a deposit, not a performance. Run easy enough that you feel almost held back; arrive at Land's End with legs still under you. From Pendeen onwards, trust that banked energy and begin to spend it deliberately. Breaking the back half into manageable segments — checkpoint to checkpoint, headland to headland — turns a daunting 70 km into a series of achievable resets. The cut-off is Sunday 01:00 at Porthtowan, giving a generous overall window, but the course's attrition is relentless and many runners who feel strong at halfway do not finish.
Fuelling & Crew Access
The Arc offers well-spaced crew access at five points: Porthleven (40 km), Penzance (61 km), Land's End / Sennen (90 km), St Ives (124 km) and the finish at Porthtowan (161 km). These are the moments to restock calories, change wet kit and address any foot issues before they become race-ending problems. Between crew points, particularly on the rougher northern sections, you must be self-sufficient. In January conditions, caloric demand is high — cold, wind and the mechanical cost of technical terrain burn energy faster than most runners expect. Prioritise real food at crew points where possible, keep easy-to-digest carbohydrates moving through the later stages, and do not let the excitement of reaching Land's End at 90 km cause you to undereat or under-kit for the harder half still to come. Sodium and electrolyte management matters in wet, cold conditions just as it does in heat — do not neglect it because the temperature is low.
Conditions to Expect
The Arc of Attrition runs in January on the Cornish coast, and the name is not ironic. Atlantic weather systems can roll in rapidly, bringing sustained rain, strong winds and near-zero visibility on exposed headlands. The path becomes deeply muddy and slippery in wet conditions, particularly on the clifftop sections where grass gives way to bog. Temperatures are typically cold but rarely freezing at sea level; the real enemy is wind-driven rain and the long, wet night that follows. Almost every runner will experience at least one full night of darkness — mandatory kit requirements exist for good reason and should be taken seriously, not minimised. Footwear choice is critical: the combination of rocky scrambling, muddy path and beach crossings means a shoe with both grip and protection is essential. Come prepared for full winter coastal conditions regardless of what the forecast says at race week.
Race Arc 100 – Arc of Attrition by UTMB with Crux
Get the strategy, fuelling and crew plan dialled for this exact course — built from the real route, climbs and cut-offs. Your first race is free.
Plan this race — freeCourse profile
Checkpoints & cut-offs
✓ Course data verified against the official source (2026-07-05) · official source
0 km · 24 m · —
17 km · 31 m · Fri 16:35
39.7 km · 5 m · Fri 20:30
63.7 km · 6 m · Sat 01:20
81.2 km · 58 m · —
88.6 km · 65 m · Sat 07:35
104.7 km · 70 m · Sat 11:20
132.3 km · 4 m · Sat 18:50
142.9 km · 6 m · Sat 21:00
154.6 km · 6 m · Sat 23:50
161.9 km · 100 m · —
More races
More UTMB World Series
More in United Kingdom
Similar distance (100 miles and beyond)
Racing Arc 100 – Arc of Attrition by UTMB?
Get a complete race strategy — pacing, fuelling, crew plan and the crux moments — built on this exact course.
Plan your race in Crux →Strava is your training. Crux is your races.