"We talked about it and the climb was taking longer than we had planned," Koch said. "We'd climbed 1,000 meters in eight hours and we had another 800 to go, which would have been slower and taken us even longer. We needed better conditions to climb it in the time we allotted."

The decision also may have closed the book on Koch's decade-long quest to be the first person to snowboard the highest peak on each of the seven continents. When he wasn't carving turns in a remote corner of the world, Koch survived an immense avalanche on Mount Owen in 1998, rehabilitation from numerous injuries and negotiated the tricky hallways of expedition fund-raising for a chance to fulfill his dream. After months of single-minded focus, a wave of emotion broke over the 34-year-old mountaineer when he and Chin returned to base camp after turning back.

"It was a huge relief and there was also sadness," Koch said. "The first call I made was to my parents to let them know I was safe. Then I called another friend and just cried; there were 10 years that went into this and a lot of hard work, hopes and dreams. I don't like to not succeed."

Check out Koch's latest interview. Click here.

The trip took months of preparation and patience. Not content to merely make snowboard turns from the summit of the world's highest peak, Koch's goal was an alpine-style ascent and descent of the direct North Face of Everest via the Japanese and Hornbein couloirs. The team elected to forgo supplemental oxygen and climb and descend quickly, without high camps. The route had been successfully climbed six times, but the only person who attempted to snowboard the route, Frenchman Marco Siffredi in 2002, disappeared shortly after dropping into the Hornbein Couloir and was never seen again.

After securing funding and sponsors, arranging for visas and assembling the team, Koch, Chin and base camp manager Eric Henderson arrived at Tibet Base Camp (also known as Chinese Base Camp) on July 23. The team quickly moved up in elevation, establishing Advanced Base Camp and beginning the long acclimatization process.

"Right out of ABC was a tiny little hill on top of which was where our bathroom sat," Koch said. "You could gauge how acclimatized you were by how hard you were breathing while climbing to the throne."

While the team adjusted to the altitude, Henderson collected snow observation data, cooked the team's meals, and bolstered morale with a continuously positive attitude. Added to the team on the suggestion of Chin, Henderson's contributions could not be overstated, said the expedition photographer.

"Eric was the ultimate support person," Chin said. "He was the team member that had the perspective and he was really key in making this trip the trip that it was."

Henderson joined Koch and Chin for forays up nearby peaks, provided Web updates while the duo was climbing, and was consulted before all major decisions were made. "It was a different experience for me because I wasn't living under the axe for two months," Henderson said. "I was able to look at the area as a spiritual landscape in front of me without living with the threat of climbing the face like they did."

On August 6, the trio climbed Changzheng, a 6,977-meter peak that towered above ABC. The exhausting excursion let Chin and Koch an opportunity practice ascending 4,000 vertical feet in a single day and also allowed all three climbers to make some turns. Though visibility was poor and snow conditions were variable during both the climb and descent, Koch said the climb was an important success after little more than two weeks at base camp. "Those turns made us feel good and gave us a psychological and emotional lift, which was huge," he said. Shortly after their ascent of Changzheng, the team established Camp 1 at 19,300 feet, where Chin and Koch planned to launch their summit bid.

The First Attempt

After extracting Lakpa, the climbers removed their packs to rest when they heard the sound of a serac collapsing somewhere far off in the mist. "It sounds like a car crash - it's really distinct," Koch said. The noise quickly changed from a distant rumble to a deafening roar that was directly above the team. The team's exposed location offered no shelter and there was no time to move. Fifteen seconds later the climbers felt the air blast that accompanied the serac fall. Though they were prepared for the shock wave, the blast pushed Chin back several feet and blew his ski poles and pack containing his camera gear more than 200 feet. The entire party was covered with several inches of snow from the serac collapse.

"We regrouped and at that point I was feeling vulnerable," Koch said. "The couloir we were heading for has a big serac and I thought, 'If that goes, we're toast.' I took that serac fall as the final sign." The rest of the team agreed with Koch's assessment and turned back before even reaching the face they hoped to climb.

One final chance

Low on supplies and with their time on the mountain running out, the team endured unsettled weather with afternoon clouds and snow showers for several days. Finally, on September 9, the climbers departed their mini-camp at the base of the face, where they had been waiting for two days, for a final summit bid. "We were at the base of the face and the full moon was rising over the summit; it was just amazing," Koch said.

This time, Koch, Chin and the two Sherpas made their way onto the North Face and began climbing the Japanese Couloir, the lower portion of Koch's intended snowboard route. "It was an intense experience to see them shrinking in size under the full moon as they climbed higher and higher on the mountain," Henderson said. "It was definitely nerve wracking. It was as though I was watching two kids leave for school for the first time."

Conditions made for slow climbing, however, with the snow surface not as firm as the team hoped and dangerous ice lurking underneath the surface. Despite the new precipitation, the face hadn't avalanched recently, which concerned the team. "I felt more vulnerable and exposed on that face than I ever had before," Chin said. "Looking at 9,000 vertical feet from the bergschrund was a pretty intense moment."

When the team concluded conditions weren't safe to continue, Koch strapped on his snowboard and Chin began downclimbing and snapping photographs. Ironically, the deep powder that had hampered the climbers upward progress made for excellent snowboarding conditions, allowing Koch to fulfill his dream of carving turns on Everest.

According to Chin, the day after the team left the face, a fracture line was visible across the top of the Japanese couloir, right above where the team had decided to turn around. "There was a time when we didn't even feel like we were going to get onto the face," he said. "Just to be up there and climbing was awesome. There were so many cool aspects to the trip; we had the whole mountain to ourselves and I learned a ton. I'm more confident and prepared now in how I approach 8,000-meter peaks."

Koch, too, was philosophical about the outcome of the costly, time-consuming, and ultimately life-transforming, mission. "For this peak in particular it wasn't about the summitting and snowboarding. It was about the process, about the path," he said. "I couldn't have asked for two better partners and the Sherpas were awesome as well. We had the whole mountain to ourselves for two months, and that's an experience that hardly anyone has nowadays."