Families, business rivals and individual triathletes are set to go head to head in a racing challenge as part of Britain's most beautiful marathon weekend.

Competing to be the best, individuals or teams of three will tackle the Salomon Kielder Marathon course in the heart of Northumberland in the form of a duathlon relay event. The Kielder Run Bike Run follows the 26 mile course around northern Europe’s largest man-made lake, Kielder Water.

Former Olympic athlete and event organiser, Steve Cram, said: “With the marathon, a lot of people enter as a challenge to themselves but the Run Bike Run can be a team challenge or an individual challenge so it increases the competitiveness. We’ve had several teams enter from the same company and colleagues using it as a corporate challenge but also family members racing against their friends.”

Entries for the Kielder Run Bike Run are now open at www.kieldermarathon.com. Teams can enter as a team of three or as an individual triathlete. Team categories are corporate, family or team. There is also the Kielder 10k on the same day. Entries are also open for Kielder Junior Runs - these races are taking place at the same time as the main marathon event on Sunday 7 October for children aged seven to 15.

Kielder Water & Forest Park, which spans 250 square miles, is home to the largest forest in England and Premier Park campsite Kielder Water Caravan Park. Why not book a pitch and enjoy the marathon weekend, whether taking part or spectating?