Why is cotton a bad idea?

Cotton holds moisture, loses its insulating properties when wet, and dries slowly. At altitude, getting cold and wet can lead to hypothermia even in mild weather.

Do I really need sunglasses if it's cloudy?

Yes. UV rays penetrate clouds and bounce off snow and rock. Snow blindness is a real risk at high altitudes, so keep your eyes protected at all times.

How to Pack for High-Altitude Destinations

Pack using a strict layering system to regulate body temperature and prioritize UV protection. Because air is thinner and drier at high elevations, you must focus on moisture-wicking materials and gear that shields you from extreme sun exposure.

Master the three-layer system. Pack a moisture-wicking base layer (merino wool or synthetic, never cotton), an insulating mid-layer (fleece or down jacket), and a windproof/waterproof outer shell. This allows you to shed or add layers quickly as temperatures fluctuate throughout the day.
Protect your skin and eyes. UV radiation is significantly stronger at altitude. Pack broad-spectrum SPF 50+ sunscreen, lip balm with SPF, and category 3 or 4 sunglasses. A wide-brimmed hat is non-negotiable.
Hydrate and moisturize. Bring a 2-liter hydration bladder and a dedicated moisturizer or heavy-duty hand cream. The air is extremely dry, which leads to rapid dehydration and cracked skin.
Prepare your personal pharmacy. Pack ibuprofen for headaches, electrolytes for hydration, and consult your doctor about acetazolamide (Diamox) if you are traveling to areas above 2,500 meters (8,200 feet).

Why is cotton a bad idea?: Cotton holds moisture, loses its insulating properties when wet, and dries slowly. At altitude, getting cold and wet can lead to hypothermia even in mild weather.
Do I really need sunglasses if it's cloudy?: Yes. UV rays penetrate clouds and bounce off snow and rock. Snow blindness is a real risk at high altitudes, so keep your eyes protected at all times.