The height of Olympus Mons above the base is about . There is a vertical escarpment of about , above which is the flank of the volcano crater with a gradient of about 6%. The details of mountaineering are described as the group ascends. Members take oxygen on the upper part of the ascent, and strong winds develop. During the climb, one person suffers a broken arm because of a falling rock, and is taken down by a few others; another suffers pulmonary edema because of ascending too rapidly, and is taken to a lower camp to ascend more slowly.