Running across the Sahara

Three men have successfully crossed the Sahara Desert by running the equivalent of two marathons a day for 111 days straight. The journey took them through Senegal, Mauritania, Mali, Niger, Libya and Egypt -- from the waters of Senegal to the Red Sea.

Temperatures ranged from above 100 degrees in the day to below freezing at night. Intense winds from every direction make it difficult to see -- even, at times, to breathe. The three men are experienced adventure racers, but the Sahara was their ultimate challenge.

Many have said the trek was impossible, and -- while he calls it a "life changing event," runner Charlie Engle, 44, also says he would "never consider crossing the Sahara on foot again."

The men's journey was captured by a film crew, who plan to create a documentary narrated by Matt Damon. You can also learn more by visiting the National Geographic site devoted to the trip.

Amazing.