View source for Worlds Toughest Ultramarathons

There are many events that claim the title of Toughest Race in the World and it becomes clear that each event makes that claim based on unique features of the event. This then is a list of ultramarathons who have a reasonable claim to the title, in no particular order.

* [[Badwater Ultramarathon|Badwater 135]]
* [[Barkley Marathon|Barclay 100 Mile]]
* [[Marathon des Sables]]
* [[Self-Transcendence 3100 Mile Race|Self-Transcendence 3100 mile race]]

==Other serious endurance races==

* Iditarod Invitational (Mushing)
* Race Across America (Cycling)