Poll: Which is the toughest ultramarathon?

Which is the toughest ultramarathon? It’s a question that’s often asked, but hard to answer definitively.

Some will argue that it’s always tougher to take on a single continuous event, rather than a stage race. Is it harder running in the heat of the desert or the cold of the Arctic Circle? Does a race with thousands of metres of vertical ascent beat one that crosses rivers through a humid jungle?

The debate will go on, but you can have your say below: