ExplainerThe 6 hardest ultra marathons on Earth, from Hong Kong to the Artic
- ‘World’s toughest ultra marathon’ is a tag line that accompanies a host of races, but which is actually the hardest?
- Pain and suffering is part of the sport, and these events pack plenty of both

The “World’s Toughest Ultra Marathon” is a tag line that accompanies a host of races and events, but more often than not it is merely a marketing slogan.
Some of the races deserve such a distinction, while others are just great at promoting themselves.
In essence, there are so many variables in races – such as weather, training, depth of field, and personal preferences – that one person’s “toughest” is another’s comfort zone.
Let the debate rage on about which race is truly the toughest – but here are six that are indisputably in the conversation.
Barkley Marathons
Nicknamed ‘the race that eats its young’, the Barkley Marathons is notorious – the finishing rate speaks for itself (or rather, the lack of finishing rate).
The first edition took place in 1986 as a 55-mile race and it was extended to 100 miles (160km) in 1989. It was not until 1995 that anyone finished the full 100 miles in the 60 hour limit.