Patagonia Silkweight T-shirt
I dont think any fabric on earth is going to keep you all that comfortable, but Id still vote for synthetics in most cases. Youll find they simply dry much faster than cotton, as well as being less inclined to develop and give off a bad odor when youre unable to do any laundry. And, Im completely convinced that fast-drying actually does help cool you through the evaporative cooling process.
So, yes, Id pack Patagonia Silkweight T-shirts ($32) and boxers ($26; www.patagonia.com). Also, you could try some items made with CoolMax ($20 at L.L. Bean; www.llbean.com). Ex Officio (www.exofficio.com) makes some excellent wicking, fast-drying underwear designed for hot, sweaty travelers. Briefs are $18, boxers $24, in several styles.
Im not completely dogmatic on this point, and chances are, if I were making this trip, Id pack in some cotton T-shirts and maybe even a few pairs of cotton underwear. I dont dispute cottons comfort in hot weather; I just think it has limitations, especially for long-term wear.
Otherwise, Im sure you know the drill: Keep your head protected, drink plenty of liquids, and try to avoid hiking during the hottest part of the day. Youll actually adapt pretty well to the conditions if you dont rush things.
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