The Northumbrian

The Northumbrian is an ultimate endurance event held in the stunning Kielder Water and Forest, Northumberland. It features full and half iron-distance triathlons, including a 2.4/1.2-mile swim in Kielder Water, a 112/56-mile bike ride through scenic valleys and challenging roads, and a 26.2/13.1-mile run along forest trails. The 2025 edition introduces new ultra trail runs: a 50K with 700m elevation and a 20K with 400m elevation.

Participants enjoy a challenging course combining natural beauty and adventure, with on-course support, nutrition, timing, and finisher rewards included. The event celebrates fortitude and achievement in a breathtaking setting. Visit the organization's website for the most recent information.