One of WMI’s messages about hypothermia in the wilderness is that it’s much easier to stay warm than to get warm. This prevention theme resonates through-out wilderness medicine, where resources are limited, environmental conditions are challenging, and evacuation can be lengthy and difficult. Being prepared to care for yourself every time you leave the roadhead is good medicine.

I’m often struck by the vast differences in the packs I see when I’m day hiking. They range from mine, which is usually the largest, to people with nothing but the clothes on their backs and perhaps the water bottle in their hand. They could be minimalists who enjoy a wilderness experience with limited gear, but it’s more likely they are simply not thinking about the possibility of misfortune or spending the night out. They are unprepared.

What might you bring in your pack? You can’t carry everything. You need to be light, yet wise. If your pack is small, you might regret leaving out essentials. If it’s too large, you won’t enjoy the trip and you might have a tendency to dump things at the last minute.

Let’s look inside my pack. In the main compartment is a spare fleece jacket, a wool sweater, and, secured from moisture in a plastic bag, my down parka. I have a pair of fleece pants, and in plastic bags I keep spare socks, gloves, and a wool hat. I’m probably wearing a layer of polypro, and my wind clothes, hat, and gloves. It’s still winter in Wyoming, so I bring lots of insulation. Until you’ve spent an unanticipated winter night away from your sleeping bag, you might not know what you need to stay warm, or how miserable this night can be. I’ll pack differently in the summer, deleting the down parka, but I’ll add rain gear. Optimism is a great approach to life, but a poor choice when packing. Plan for challenging weather, not a sunny day.

In the pack bottom is a stuff sack with essential survival gear. To start a fire, I have matches in a waterproof container, a flint, a lighter, and a film canister with cotton balls soaked in petroleum jelly. These light readily with a spark, burn long and are very helpful as a base for your kindling. I also have a signal mirror, whistle and a bit of orange surveyor tape for signaling. Mirrors help us be seen from afar, especially the air, and whistles carry farther than voices. I have a heavy-duty garbage sack, the poor man’s bivouac sack. If needed I can crawl into this to spend the night, or use it as a rain jacket. And I have a small pot to heat water for the hot drink that warms and nourishes my body and my spirit when I’m cold.

In my top pocket is my navigation gear and a small first aid kit. I’m a map-and-compass guy, but I do own a GPS and will occasionally bring that along. Likewise, I’ll commonly have a cell phone, which is buried in my pack and has not been used. My headlamp is both a signaling and navigation tool. My personal first aid kit has items I can’t improvise: an airway barrier device, a pair of gloves, a roll of tape and an ace bandage. If I’m out with family or friends, I’ll carry a larger kit.

I also bring lots of food and water and a bottle of iodine tablets (potable aqua) to disinfect water. Lurking in a corner of the pack is a small roll of duct tape and some parachute cord. My knife is in my pocket. Outside the pack is a rolled short foam pad to insulate me from the cold ground or snow.

The equipment is helpful, but it won’t protect from poor habits and decisions. Take your time and think. Hopefully you can be warm and reasonably comfortable with the gear in your pack while you make a good plan.

Preparation for the unexpected night away from a tent and sleeping bag starts with the assumption that, despite my best plans, things can go awry. Have I taken the time to think through, or better yet, write a route or time control plan? Does anyone know where we’re going and when we anticipate returning? Is there a local rescue group I can depend on, or am I on my own? Am I ready to lead myself through tough times? This key to tolerating adversity is not found in your pack, it’s in your head, and your heart.