Adventurer Colin O’Brady on Wednesday accomplished what he had dubbed “the Impossible First,” becoming the first person to complete a solo, unsupported crossing of Antarctica.

With a push of 32 hours after leaving his last camp on Christmas morning, the 33-year-old from Portland, Oregon, reached the edge of the Ross Ice Shelf on Day 54 of his expedition. He had covered almost 80 miles since his last sleep.

Briton Lou Rudd, who set off the same day — Nov. 3 — on the same quest, on Wednesday had about 70 miles left, according to his expedition’s tracking map. It estimated a finish on Saturday. The full trek is about 935 miles.

O’Brady’s Instagram post from the finish post read in part: “While the last 32 hours were some of the most challenging hours of my life, they have quite honestly been some of the best moments I have ever experienced. I was locked in a deep flow state the entire time, equally focused on the end goal, while allowing my mind to recount the profound lessons of this journey.”

O’Brady had reached the South Pole on Dec. 12, a day ahead of Rudd.

Pulling large sleds loaded with all their supplies for the trip — about 350 pounds at the start — the two men had followed the shortest sanctioned route that is considered shore-to-shore of the Antarctic continent. From the edge of the Ronne Ice Shelf they traveled almost 600 miles to the pole, then took a turn of about 90 degrees toward the Ross Ice Shelf.

Rudd, 49, is a captain in the British army. He has Antarctic expedition experience, and he had announced in April his intention to go for the solo/unsupported first.

The October announcement of the same goal by O’Brady came as a surprise. A triathlete and alpinist, he was a relative novice to polar trekking.

Rudd had been a friend of Henry Worsley, a fellow British army officer who in 2016 had completed 900 miles of an unsupported traverse when he called for a rescue. Suffering from exhaustion and dehydration, Worsley died of organ failure before he made it home.