At 6:01am my running buddy and I started going up. It was a pretty warm day, which allowed us to go with shorts, trailrunning shoes and very light clothes. The route ascends in the middle of penitentes, snow and rocks, but we were able to move fast, so when we reached 4700m, it was only 08:33 in the morning. Then the trail got steeper and it was possible to see astonishing peaks such as Marmolejo (6108m).
When we reached 5600m it was possible to smell the sulfur of the volcano, and with a little bit more of 250m of elevation gain left, it was only about going onwards and upwards.
The last 20 minutes of the route we were going next to the crater, but it is necessary to continue since this is not the actual summit. International Summit (5856m) stands way behind.
When the watch said 5h 17min 10sec, we were standing at the border of Chile/Argentina, still with a warm day, Marmolejo in front and the crater behind.
A day to remember.