On our second day on the mountain, we walked up the valley of the Río Cepo to Federación, 4,000m above sea level. It took about three and a half hours. In the night I'd felt the altitude a bit, waking up a few times when I suddenly had to take a really deep breath, but today I felt very acclimatised and found the going easy. We got to Federación in the early afternoon, at the same time as some heavy clouds. We were under the west face of El Plomo but we couldn't see it at all.