Incahuasi (6,641m) - Provincia de Catamarca, Argentina

This huge volcano, the 12th highest mountain in the Andes, lies just south of the paved road from Fiambala to Paso San Francisco, and as it is so accessible receives more ascents than most of the other 6,000ers in the area.

After taking 2 1/2 days to cycle up from Fiambala to Argentine immigration at Las Grutas we headed off the main road, cycling 2kms towards the mountain to some termas. After spending the night there we continued on a rough track for 9kms towards the mountain by which stage the surface was so bad that we decided it'd be quicker to leave the bikes and continue on foot.

The weather had been unsettled on our cycle up to Las Grutas, with lots of threatening looking clouds, and some thunderstorms at night. As we walked 4 hours from the track to a low camp at 4,600m, lots of ominous lenticularis clouds appeared to the east of the mountain. We probably should have turned back at this point (and would have done had we known what was to come), but as the weather was nice every morning we decided to continue. During the night there was a big storm a few kms away to the east.

The following day we continued, going between the dark volcancitos which lay between us and the mountain, before descending 50m to the usual base camp at 4,950m. The weather, which had been nice, took another turn for the worse, and as we climbed up the sandy NE gulley aiming to camp at the col at 5,700m, we were overtaken by a hail and lightning storm and spent half an hour crouching behind a rock waiting for it to pass. We were at 5,400m at this stage and when the weather improved, decided to stay here to camp. We were well acclimatized so didn't think we'd have any trouble summitting from this low down, and the weather remained bad up at the portezuelo so this seemed like the sensible thing to do. However, there was no flat ground around (apart from a couple of exposed spots that we didn't fancy camping on in case the lightning returned) so we spent 2 hours chipping a platform out of the ice in the gulley using rocks and some tent pegs. As there was no running water in the vicinity we melted the chippings to drink.

The weather was still overcast when we went to bed, but when we woke at 07:00 it was clear again. We set off just after 08:00 and followed the clear path for an hour to the portezuelo at 5,693m. There is meant to be water near here, though it wasn't that obvious to us as we walked past where this was. From the portezuelo the going became steeper, firstly up sandy/scree slopes, then up the rocky NE ridge to the right/north of the large penitente field. We had to use our hands at a few of the steeper sections on the ridge.

We emerged onto easier ground at 6,225m and from there the route to the summit was clear. We initially walked across a plateau, then headed between 2 penitente fields at 6,434m. The weather began deteriorating and we were walking through clouds for this section, with visibility often down to 100m. After passing through the penitente fields we climbed up the gentle slope to the summit (6,641m), arriving 4h45 after leaving camp. Here the weather was clear to the west, so we had views of the stunning Laguna Verde in Chile, and could just see El Fraile. Ojos, Walter Penck and Nacimiento were all obscured by cloud however. Unlike some of the other mountains in the area the summit is very obvious, even more so as it is marked by a 1m tall metal cross, and there is also a plaque left up there by the Reynoso family to a friend who died in the Peruvian mountains.

The weather was now looking pretty bad so we didn't stay long on the summit, then took the most direct route back to camp. Descending to where the streams emanating from the 2 penitente fields (we'd passed between on the climb) go off the edge of the plateau and following this gulley directly to camp. The first part was steep with loose rock, but after a while it became easier. The last few hundred metres were on sand and as we could tell a storm was coming we ran down these, arriving back at camp 1h45 after leaving the summit.

The next few hours were the scariest of our lives. The first storm duly arrived, but though our tent was pelted with hail, the lightning never came too close. A couple of hours later however and a second storm came very close, far too close for comfort. For an hour we sat squatting in our tent as every 5 seconds a lightning bolt struck the mountain. Hundreds of times we heard roars of thunder and we lost count of the number of times that the thunder arrived simultaneously with the lightning. It was terrifying. We were thankful that we'd put up the tent in the shallow gulley the day before, because if we'd been up on the portezuelo during this storm we would've been in a whole heap of trouble.

After the longest hour I can ever remember the storm finally passed and we were able to relax and lie down, which was very welcome as our feet had long gone dead. (If anyone else is unlucky enough to be caught in a tent in a storm, here's some advice as to what to do.)

During the night there was another big storm, but it wasn't too close, and in the morning (sunny again) we got the hell off the mountain. It was only 3 hours back to the bikes, the first part walking in 10cm deep snow that had fallen the night before. We were soon soaking in the termas again and spent the night at the refugio at Las Grutas. Much as we love the Andes this put us off for now, so we decided to change plans and leave climbing Veladero, Tortolas and Olivares, which we'd planned on climbing in the next month, for another time and head to the Argentine Pampa instead.

Some GPS points

Description	Lat	Long	Alt
Left bikes	26.96700 S	68.19588 W	4,060m
Low camp	26.99999 S	68.24476 W	4,622m
Usual basecamp	27.01368 S	68.26041 W	4,954m
High camp	27.02448 S	68.27058 W	5,401m
Usual high camp on col	27.03285 S	68.27296 W	5,693m
Top of NE ridge	27.03385 S	68.28124 W	6,225m
Between 2 penitente fields	27.03035 S	68.29048 W	6,434m
Incahuasi summit	27.03374 S	68.29663 W	6,641m
On direct route down to high camp	27.02904 S	68.28287 W	6,181m