What are must-have items in an emergency kit for a multi-day hiking trip?
Obviously, what you decide to pack depends on your trip and the environment, but these are the staples I always bring along:
Navigation: You always need to be able to figure out where you are and which way you need to head to get out. In my opinion, a map without topography isn't a map (unless you're on very flat land).
- GPS with extra batteries
- Local trail map with detailed topography
Warmth & Shelter: You need to be able to get warm and protected from the elements. I always bring a sleeping bag if I know it'll get cold at night, even on single-day hikes where I don't plan on sleeping in the backcountry. God forbid you get lost and have to spend the night, it's worth the extra few pounds for peace of mind.
- Waterproof matches
- Synthetic tinder (If it has rained recently, it'll be hard to find dry sticks for starting a fire)
- Space blanket
- Trash bags (Infinitely usable as waterproof containers or shelters)
- Sleeping bag
Rescue & Signaling: If you fall and break both your legs or get your arm pinned under a rock, you need to be able to make a commotion and attract attention.
- Flashlight with extra batteries
- Signaling mirror (I personally don't bring one, but I know a lot of people say you should)
Food & Water: This isn't just so you can stand on a mountain eating a Nature Valley bar like they do in the commercials. If you need to survive for a few days, you'll appreciate the sustenance.
- Pot for boiling water
- Water bottle with clean water
- Granola bars or bagels
General Survival: If you have to make shelter, conduct first aid or perform any other basic camp tasks, you'll probably need this stuff anyways.
- Knife or multitool
- Rope or parachute cord
- Duct tape
- First Aid Kit
Edit: As Phil mentioned, you should always bring a cell phone. Keep it in a waterproof bag, and turn it off so you're not disturbed. But having one in a pinch is the difference between being able to summon help for yourself and sitting around hoping someone is out there looking for you.
There are different types of being stranded; there's "lost the trail an hour in" stranded, "lost the trail twenty miles in" stranded, and "broke a leg" stranded, just to name a few.
Considering your question
- Multi-day Hiking -- Therefore I assume you have standard hiking gear and are not asking for that. Also assuming that you're not going to be nearby a car (car-camping).
- Multi-day trip -- You're going to be out a ways.
Your emergency kit should be gear that never leaves your person. If I get stranded away from my gear, I have this kit. People have died from going to take a leak in the middle of the night and getting lost. Your general hiking equipment is your "gear," moreso than your "emergency kit".
Why "never leaves your person"? You are at primary risk of two types of problems. For simplicity we will assume the worst case in both, that you have lost your group.
- Injury -- If you become seriously injured, your world will be limited to a very small area. Self rescue is limited.
- Lost -- If you become lost and separated, because it is a multi-day hike, rescue will likely be more than a few hours away. Assuming you cannot self rescue, you may be in for a long wait of a week or more depending on when S&R is notified of your absence.
If you won't have your emergency gear with you, then it's not an emergency kit. With that in mind, I build my kit for three things
- Light -- I never feel burdened and so I never set it down.
- Small -- It's easy to attach to whatever I am wearing, or just strap to my leg.
- Supportive -- My kit may not be shelter, but it will help me make it. It may not be food, but it will help me secure some. It may not be rescue, but it will help them find me.
- Knife (big enough to use, but not super heavy)
- Space blanket (for warmth)
- 50' paracord (a million uses)
- Trash bag (rain cover, distillation tool, lots of uses here)
- Water purification (iodine is light and works)
- .5 liter water container (iodine tabs will do .5 liter. I carry a .5 liter platypus, but it's your choice, you need a water container)
- Fishing line & hooks (I carry about ten. 1 is not enough, 100 is too many)
- 200 calorie snack (200 calories won't keep you alive, but I want something to nibble on while I find food)
- Compass (assuming you can use it)
- A few oz of salt (good to eat, can double as a temporary fix for infections)
- Whistle (I prefer the ridiculous whistles that can be heard really far away)
- Scout flint & steel (learn how to use it)
- Small flashlight (again I'm on the super-low-weight side, so I carry a Fenix)
- Based on Hartley's point, I think I will be adding my super-small Snow Peak .75L pot
Any kit is nothing without knowledge. You need to know how to use all this stuff, how to make your own shelter, and preferably all the local edibles and how to find them. Before you go out on a day hike, I recommend you practice with this gear to make sure you can do the minimal of:
- Build a shelter
- Start a fire
- Collect and purify water
- Signal with mirror, fire, and whistle
This stuff never leaves my emergency kit. For any of it that I also use regularly in camp, I have a second one. My emergency kit is for emergencies only and is separate from the rest of my gear. It has its own pouch that I keep with me (not with my pack).
I hike the Appalachians. It gets cold, but not Canada cold, and it's not desert. This would likely need to be tweaked for extreme cold or heat.
Hartley (and Phil) pretty much have it covered, but I'd add a couple of things.
- A bothy bag - basically a quick emergency shelter for 4-6 people that packs down nice and small
- High energy/sugar foods - mars bars, peanuts, jelly, energy bars etc
Also, it's a little over the top, but we take emergency cards that you fill out with vital information like the nature of the emergency, how many people in the party, an emergency contact for your party, your location etc, and send someone with the card to get help.
For a multi-day hike obviously you'll have a tent which can be very useful in emergencies.
Just additional two cents, but don't underestimate the visibility of a green laser pointer at night. In survival situations and with light fog, a green laser pointer shooting up in the sky will make your position extremely clear.
For the exact same reason, don't use it with airplanes around. They hate that, and you will be found and prosecuted.
The other answers focus on general survival kits, but don't give much coverage to first aid kits.
Here's what you need in a first aid kit, in order of importance:
- Training. It takes up no space, weighs nothing, and is more critical than anything else.
- A cell phone. In a serious medical emergency, there's no piece of equipment you'll want more. Take it even if you don't get reception for the whole excursion. It can still shave hours off the response time because it will likely get a signal a few miles before you've reached civilization.
- Two pairs of rubber gloves to protect yourself in case you have to treat bleeding.
- An epi pen. Someone in your party may be allergic to bee stings and there's no way to improvise this.
- Aspirin and Advil. The former for any heart attack symptoms and the later for general pain and swelling.
- Antiseptic wipes and band aids to prevent infection from minor cuts and scrapes.
That's it. Everything else you might need can be improvised from regular hiking equipment and the ten essentials.
My list may not sound as sexy as some of the others, but it's been tested in the field. I'm a former EMT and climbing guide, and I've faced multiple life-or-death medical emergencies in the wilderness.