Hundreds of people took to the fells to raise thousands of pounds for charity. They had the choice of tackling 10 peaks in 10 hours or five in five hours.
Organiser Duncan Booth who has MS says he hopes raising money will one day find a cure for the disease.
One of the world's most gruelling foot races began in the Lake District this morning.
Competitors will run a marathon a day around Windermere until next Sunday as part of the Brathay ten in ten challenge.
Fifteen runners were selected for the charity event, which is widely regarded as one of the ultimate tests of endurance.
Ryan Dollard reports:
To find out more about the work Brathay Trust does, and how you can sponsor competitors, visit the website here.
61-year-old John McCann is the oldest competitor taking part in the Brathay Trust marathon, and he knows he is going to have to pull out all the stops to complete the monstrous challenge:
Legendary Cumbrian fell runner Joss Naylor says that the Brathay Trust marathon is no mean feat:
Mike Bushell from the Brathay Trust believes that the Windermere marathon is arguably the toughest in the world:
A group of runners are about to begin an epic marathon challenge that will see them tackle ten marathons in ten days.
The Brathay Trust Windermere 10in10 Marathon gets underway at 9.30am from Brathay Hall in Ambleside.
Fifteen competitors are due to take part in one of the most daunting endurance runs in the world.
Runners will pound their way over 262 miles of Windermere roads and pavements to raise money for charity.