They didn't bring enough gas. They didn't drink quite enough water. And it's probably little errors like this, which may have contributed to the greater problems that they experienced later. So day two, they started climbing again at an altitude that they'd never climbed at before. The snow was very unstable because it was made of powder and so he couldn't get a secure footing or any anchors in there. It would have been like incredibly heavy climbing with this frozen suit of armour on top of them all the time. According to Joe, the last part of that face was some of the most nightmarish climbing that he'd ever done. I mean, it terrifies me to be honest