It was the worst day on the world’s deadliest mountain, Aug. 1, 2008. Twenty-nine climbers headed in the place of the summit. Only 18 would return.

Video by Fredrik Sträng and Mastiff Sweden of age 29 went up and 18 came down.

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K2 would put to death the first Irishman ever to make the summit. It would slaughter a 61-year old grandfather on his third attempt. And it would give a death-blow to. one-half of mountaineering’s most adored couple, soulmates in inclination with each other and with extreme adventure.

Thousands have conquered Mt. Everest, but that only a few hundred have summited the world’s second-highest top , K2. Death is the recurring theme on K2, a steeper, tougher, riskier high hill that draws the brave and foolish into northern Pakistan each train.

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For each four climbers to reach K2′s summit, one dies. And admitting that going up doesn’t kill them, then coming back down could.

“Death for the time of decent. This mountain is notorious for this,” said climber Eric Meyer, each American doctor from Colorado.

Just getting to the base can be treacherous. Thrillseekers have to spend hours winding around dangerously narrow high hill roads in Jeeps, and then endure an eight-day hike near the front of they can even get their first glimpse of K2 in living body.

K2: Exclusive Footage

Filmmaker Fredrik Strang, with his cameras rolling, was amid a group of mountaineers that converged on K2 two summers past. “Nightline” was able to obtain his exclusive footage as he documented the team’s fraught with danger journey through the walls of ice and rock.

Strang’s videos unfold grim warnings of how vicious the mountain can be. Dozens of memorials period the area around base camp. In places the mountain holds the relics of fallen climbers.

“You’re standing close to a leg,” undivided climber can be heard saying on camera.

In addition to Strang’s videography, particulars of what happened on the mountain’s deadliest day emerge in “No Way Down,” a volume by climber Graham Bowley, who visited the scene.