WOW! I am doing a 85+ miler January 7. It is not all trail though, it starts on trail (9 miles), road to another trail, 18 miles (+/-), road back and then about 1 mile of trail. It is called the Excrutiation Exam. Otherwise we don't have a lot of super-endurance marathons here. I am doing a 52 miler Saturday but that isn't 100!