The Northumbrian is a major multisport and trail-running endurance festival set in and around Kielder Water & Forest Park in Northumberland National Park. It combines world-class triathlon disciplines with spectacular trail running options, drawing athletes seeking a bold challenge across open water, scenic valley roads and rugged forest trails. The 2026 edition marks the fifth anniversary of the event and includes national championship status for the Half Iron distance triathlon.

Key Details

• Date & Time: Saturday 27 & Sunday 28 June 2026 — early starts for multisport and trail events.

• Location: Kielder Waterside / Kielder Forest, Northumberland, UK — a remote, scenic area known for its lakes, forests and challenging terrain.

• Organiser: Events of the North.

Event Types

Participants can choose from a range of endurance options:

• Full Iron-Distance Triathlon: 2.4 mi swim, 112 mi bike, 26.2 mi trail run.

• Half Iron-Distance Triathlon: 1.2 mi swim, 56 mi bike, 13.1 mi trail run — host of the British & English Middle Distance Championships in 2026.

• Team Full & Half Triathlon Relays: Relay options for teams of three covering the same distances.

• Trail Runs:

  • 50K Ultra Trail Run (~48 km with ~700 m elevation).

  • 28K Trail Run (~27 km with ~400 m elevation).

Race Description

Swim: Competitors enter and exit the stunning Kielder Water reservoir — usually inaccessible for swimming outside of this event.
Bike: The cycling legs traverse scenic valley roads and border countryside, with partial road management and full marshalling.
Run: Running is on varied forest trails with sections shared by both triathletes and dedicated trail runners, finishing at Kielder Waterside near the event village.

What’s Included

• Official timing and course support for triathlon and trail events.

• Trail aid/support stations and marshals at key points.

• Finisher medals and event goody items. 

• Scenic venue with a strong supporter and participant community.

Additional Information

• Championship Status: The Half Iron-Distance triathlon serves as the British & English Middle Distance Championships 2026.

• Trail Run Indexing: The 50K and 28K trail runs are UTMB Index events, contributing to qualification for global trail racing series.

• Team Entries: Relay teams can enter full or half distances for triathlon categories.

• Early Starts: Swim legs typically begin early on Sunday; trail runs start the day before with early-morning wave times.