The Northumbrian
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About the race
The Northumbrian, staged at Kielder Water and Forest Park in Northumberland, is pitched as the ultimate endurance test. The event features full Iron-Distance Triathlon (2.4-mile swim, 112-mile bike, 26.2-mile run) and Half Iron-Distance (1.2/56/13.1), plus Aquabike at half distance. It also includes UTMB-index Ultra Trail runs: a 50K ultra (about 48km with +700m) and a 20K trail run (about 27km with +400m).
The routes weave lake waters, forest trails and scenic valley roads, delivering a remote-nature atmosphere with on-course support, nutrition, timing, a finisher’s medal and a cycling jersey. A fifth edition in 2026 reinforces its reputation for scenery, challenge and achievement. Visit the organization's website for the most recent information.