For the past 111 days three ultra-endurance athletes an American, a Canadian and a Taiwanese have been striving for a goal most people could only describe as insane: Running the equivalent of two marathons a day to be the first modern runners to cross the Sahara Desert's grueling 4,000 miles (6,437 kilometers).
"This is 100 percent, without a doubt the hardest thing any of us have done," said American runner Charlie Engle, 44, while eating tuna and plain pasta during a lunch break about 180 kilometers northwest of Cairo on Saturday, day 108.
Engle and Canadian Ray Zahab, 38, and Kevin Lin, 30, of Taiwan, were set to finish their ultra-marathon later Tuesday at the mouth of the Suez Canal in Egypt.
In less than four months, they have run across the Sahara, the world's largest dry desert, through six countries Senegal, Mauritania, Mali, Niger, Libya and finally Egypt.
A film crew also is following them, chronicling the desert journey for a documentary from actor Matt Damon's production company, LivePlanet. Damon plans to narrate the "Running the Sahara" film.
The trek is one of extremes. The relentless sun can push temperatures to over 100 degrees Fahrenheit (38 Celsius) during the day, but at night it sometimes dips below freezing. Strong winds can abruptly send sand swooping in every direction, making it difficult to see and breathe.
Running through turbulent conditions is nothing new for these athletes who have traveled the world competing in adventure races. But they say nothing has tested their physical and mental limitations like the Sahara.
Throughout the run, the runners have been stricken with tendinitis, severe diarrhea, cramping and knee injuries all while running through the intense heat and wind often without a paved road in sight.
"This has been a life changing event," Engle said.
The runners say they undertook the challenge to see if they could accomplish something that many have called impossible. They use GPS devices to track their route and teamed up with local experts and a host of sports professionals who also followed them, along with the documentary crew, in four-wheel drive vehicles.
Typically, the three began each day with a 4 a.m. wake-up call. About an hour later, they started running. Around noon, they took a lunch break at a makeshift camp, devouring pasta, tuna and vegetables. A short nap on thin mattresses in a yellow-domed tent usually followed before they headed out on the second leg of their day's run.
Finally, around 9:30 p.m., they called it quits each day, returning to camp for a protein and carbohydrate-packed dinner before passing out for the night.
Despite the preparation and drive to finish, the runners said they often questioned mostly to themselves what they were doing. Zahab described stopping one recent day for a bathroom break only to discover the wind was blowing so harshly that he couldn't keep the sand out of his clothes. "And I thought to myself, 'What the hell am I doing?"' he said.
But Zahab kept going, as did the other two, all of whom never skipped a day. Most days the three ran a total of 44 to 50 miles (70 to 80 kilometers) sometimes a little more, sometimes a little less.
They were interviewed by The Associated Press on Saturday their day 108 on the side of a road about 180 kilometers from Cairo in Egypt's harsh Western Desert, part of the greater Sahara.
At several points in their trek, the athletes stopped near sparsely populated wells to talk with villagers and nomads about the difficulties they face finding water. That marked another goal of the run raising awareness for the clean water nonprofit group H2O Africa.
"We have seen firsthand the need for clean water, which we take for granted in North America. It's such a foundation for any community," Zahab said during day 108's lunch break. The three plan to fund-raise for the group after they return home and finish recuperating, reports AP.
"It started off as a huge motivator, especially as we passed through countries where the water wasn't clean," Engle said.
But now, as the trio's bodies have become more depleted, "The day-to-day battle to stay alive and keep moving" has become the focus, he said.