To get to the trailhead, follow the signs to the Nevado de Colima Parque Nacional from Ciudad Guzman. Follow the dirt road, passing the park entrance station, until the road levels out and further progress is prevented by the locked gate. It is tempting to go around the gate. You will be turned back by the Protecion Civil people who man a vast array of antennas, repeaters, and cells at the 12,000' level. They patrol fairly regularly on an ATV. Park near the gate, and start hiking up the road. The road section is only a couple of miles long. As you round a corner, the antenna facility will come into view at the top of a set of switchbacks. Just before you start up the switchbacks, look to the right for the unmarked but obvious trailhead. It may look good to take the ridge just left of the road, but if you take this variation, you will miss the trailhead, and join the route further up. Also, this variation takes you right through the front yard of the Protecion Civil compound. They don't seem to mind ( I accidentally took this variation, which is why I recommend the trailhead), but it does turn out to be out of the way.
Once you find the trailhead, follow the trail to the south slope of the peak. Here the trail becomes harder to follow, but there are paint marks on the rock to help (I'm glad we don't do that here). The last couple of hundred feet are 3rd class with an occasional 4th class move. Follow the marks, keep going up, and soon you will be there. The west summit is the true highpoint, but as long as you're there, traverse over to the east summit , the traverse is 3rd class (looks scary from the west summit, but once you get into it, it's all good) and fun, and you can check out the large bronze plaque over there. The west summit has a plaque as well, and a multitude of cast iron crosses, all lightning scarred. From the summit, your route of ascent is laid out before you. A fun variation, with a little tougher climbing, is to leave the trail just as you reach the toe (you'll be on the west side of the peak) of the rock buttress, and head straight up a steep chute. With careful route finding, this route is 3rd class as well, but with more climbing, and more exposure.
No gear is needed, save a comfortable pair of shoes. A pair of sneakers is all you really need. Use your own judgement for the rest.
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