If Colorado’s fickle spring weather leaves you at a loss in front of your wardrobe, you need to learn the science of layering. Luckily, class is in session with Crested Butte–based explorer Eric Larsen—the only person to visit the North and South Poles and summit Mt. Everest during the same year.

1. There are three main layers: a base layer, which should be formfitting to reduce bulk and made from wool or synthetic fabric to wick sweat away from your skin; a thicker midlayer for insulation; and a wind- or waterproof outer shell to shield you from the elements.

2. The specific garments you choose depend on your activity and the conditions. You’ll want lighter items such as a thin fleece midlayer for warmer days or high-intensity outings. Pick heavier garb—such as a down coat midlayer—for chilly activities that won’t leave you winded.

3. Use gloves, neck gaiters, caps, and other accessories to fine-tune your comfort. For example, whether Larsen is walking his dog or trekking in Antarctica, he always wears a balaclava, which he can doff on the move if he gets too hot.

4. As you warm up during your hike, ski, or snowshoe, mix and match your mid- and outer layers with your accessories until you’re warm enough to be comfortable but not hot enough to sweat. Water absorbs body heat 25 times faster than air.

5. It takes a lot more energy for your body to make heat than it does to retain it, so once you stop moving—say, for lunch or a summit beer—immediately layer up lest you waste those calories rethawing your jacket.

This article was originally published in 5280 March 2024.
Barbara O'Neil
Barbara O'Neil
Barbara is one of 5280's assistant editors and writes stories for 5280 and 5280.com.