Antarctica, that icy desert of the Southern Hemisphere, seems to call to people to cross it.

And some have. They've skied together, used wind kites and benefited from food drops to make it across the ice. But until Dec. 26, 2018, no one had done it alone and without any help at all.

That someone is Colin O'Brady, a 33-year-old American endurance athlete who traveled 932 miles over 54 days relying only on himself and the supplies he pulled with him in a sled.

The final march

Colin O'Brady calls his wife, Jenna Beshaw, upon completing his trek across Antarctica. Colin O'Brady calls his wife, Jenna Beshaw, upon completing his trek across Antarctica. (Photo: Colin O'Brady

In 2017, British polar explorer Ben Saunders attempted the feat, but he had to abandon the quest after 52 days because of lack of food. Another explorer, Henry Worsley, also attempted to cross Antarctica alone unsupported, but Worsley had to summon help 30 miles from the end of the journey. He later died in a hospital.

O'Brady, on the other hand, decided to do the last 77.54 miles in a single, 32-hour march.

"I just felt locked in for the last 32 hours, like a deep flow state," he told The New York Times via satellite phone. "I didn't listen to any music — just locked in, like I'm going until I'm done. It was profound, it was beautiful and it was an amazing way to finish up the project."

His support team, which included his wife, Jenna Besaw; his mother, Eileen; his sister, Caitlin Alcott; and his stepfather, Brian Rohter, asked him multiple questions to test to his lucidity before he set out on the final leg. Questions ranged from whether or not he understood what he was about to do, to whether or not he had consumed enough calories to reach the end of the journey.

"We had an open and honest and smart conversation with him," Besaw told The Times, "and he totally delivered."

A year of preparation

Colin O'Brady pulls his supply sled across Antarctica O'Brady's sled weighed nearly 400 pounds when his journey started. In this image, taken Dec. 10, he is less than 20 miles from the South Pole. (Photo: Colin O'Brady)

O'Brady spent a year getting ready for his trek on multiple fronts.

For the physical side of things, O'Brady trained every day at a local gym in Portland, Oregon, doing strength training, according to Men's Health. While every day was different, squatting, benching and deadlifting were all in the rotation. Cardio was also necessary since O'Brady would be pulling a sled with enough supplies to last for the whole trip. That required lots of biking, hiking and running.

O'Brady didn't want to repeat the food-based problems that had plagued previous attempts.

"People who have tried this [trek] in the past, their failures have come unfortunately from not getting that nutrition perfectly right," he told Men's Health. "I thought optimizing that is important."

To that end, O'Brady worked with Standard Process, a "whole food supplement" company that, with O'Brady's help, crafted a personalized nutrition bar tailored to his body's needs for walking across Antarctica. The size and shape of a gold brick with a faint taste of chocolate, the so-called Colin Bar supplied him with 1,150 calories to help him get the 8,000 calories he needed each day. (O'Brady and his team determined that he would actually use 10,000 calories a day, so he was still going to lose weight during the journey.) He would eat four of these bars a day in addition to oatmeal for breakfast and a protein-powder soup and freeze-dried foods for dinner.

Then there was the simple matter of figuring out how to pack the sled. According to Outside, O'Brady's sled weighed 375 pounds when he started, carrying 280 of the Colin Bars, additional food, 55 pounds of fuel needed to melt the 5 liters of water he needed per day and 75 pounds of equipment and clothing. Not included in this last category? A second pair of underwear.

A race to the Ross Ice Shelf

Colin O'Brady poses in front of the plane that dropped him off at the starting point of his trek. Colin O'Brady poses in front of the plane that dropped him off at the starting point of his trek. (Photo: Colin O'Brady)

O'Brady wasn't the only person attempting to cross the continent unsupported.

Louis Rudd, a friend of Worsley, is also attempting the journey. Both O'Brady and Rudd departed from the "Messner Start" on the Ronne Ice Shelf on Antarctica eastern coast on Nov. 3. Their goal was the Ross Ice Shelf, 912 miles away. (O'Brady's 932-mile journey included zigzagging, which added to the trip.)

For the first week, Rudd maintained a lead, but O'Brady eventually caught up and then passed Rudd, taking a sizable lead by Nov. 21. O'Brady never looked back until he reached the Ross Ice Shelf, the finish line for his journey.

Colin O'Brady looks out at the sun Dec. 5 O'Brady made sure to take breaks and take in the views offered by Antarctica. (Photo: Colin O'Brady)

After he got there, O'Brady set up camp to wait for Rudd.

"My eyes are shutting," O'Brady told The Times. "My plan is to wait here for Lou and fly to Union Glacier together."

How Colin O'Brady walked across Antarctica without any help at all
The coast-to-coast Antarctic trek took nearly two months for Colin O'Brady to complete and spanned 932 miles.