Distance: 1,131 miles
Location: Anchorage to Nome, Alaska, through some of the world's most barren and unforgiving wilderness
Mode of Transportation: Sled, with a team of 12 to 16 dogs
Known as "The Last Great Race on Earth," the Iditarod, in its 37th running, asks competitors to race over 1,110 miles through the middle of Alaska's winter, where they face "jagged mountain ranges, frozen river, dense forest, desolate tundra and miles of windswept coast." Don't forget that the wind chill is often well below freezing (Monday's temperature in Willow, the first checkpoint: -6 F), whiteout conditions are common, the day contains 14-hours of darkness, and, for most of the race, the mushers and their dogs are literally hundreds of miles from safety. Add to it that even when they reach a checkpoint, their day is not done, because they still must take care of 16 dogs at once (the dogs are the number one priority on the Iditarod: every musher makes sure each dog has food and a bed before feeding themselves). Most finish in 10 to 17 days, but if you want to win, you better do it in just nine.