Up for the challenge bookup for the challenge presents over 60 of the most extreme sporting events of the planet can you take on an ultramarathon through the searing heat of death valley or face the sub zero temperatures of the north pole marathon take to your bike and race the 2 175 of the tour de force or if you can cope with getting your hair wet oceans seven a gruelling swim across seven of the mightiest stretches of ocean might be for youreading alone is enough to give you an endorp