The Arc of Attrition, or the Arc100, is a British Ultramarathon set against the beautiful Cornwall coast. Thought to be one of the most difficult of events, completing this race is an amazing achievement, as almost half do not complete the route.

A point-to-point extreme coastal race from Coverack to Porthtowan, the Arc of Attrition takes in 100 miles of stunning and dramatic Cornish Coastpath, with competitors running in challenging winter conditions.

The route has 4010m of total elevation across its 100 miles. Whilst the route itself is hard, the primary challenge for runners is the weather rather than the land; a winter race on the coast is infamously windy, wet and cold.

Runners will complete an Arc around the entire southwest foot of Cornwall. The race has a strict 36-hour cut-off with additional checkpoints and safety cut-offs on the route. With checkpoints approximately 20 miles apart, competitors must be self-sufficient for long periods.

Almost entirely sticking to trails, there are a few sections where the route joins up with the road, but only where the South West Coast Path does the same. There are only two spots at which the race departs from the path: Cape Cornwall and St Ives Island.