WATER: This is the number 1 thing that your body requires. I often carry a bit of water in a flexible Platypus container. They're suprisingly durable and more comfortable to keep in my pocket than a rigid container.

The reality is that you can't carry enough water to survive very long, so be sure that you can find and filter water. My Garmin InReach is useful for finding water (ponds, lakes, streams, etc.). If you can handle 2 ounces, then I highly recommend the Sawyer MINI water filter. I use it to refill my water bottles on ultralight backpacking and mountaineering trips. At the very least, toss several MSR Aquatabs into your first aid kit. Drop one in your water bottle, wait 30 minutes, and you'll have safe drinking water.

STAY WARM AND DRY: After dehydration, hypothermia is probably the next most likely way to die, especially if you can't keep dry. An emergency blanket is great. If you can spare 3.8 ounces, I like the S.O.L. emergency bivvy. It's more thermally efficient to sleep in a sealed tube. I've spent the night in one at 12,000ft in a snow cave. I had a little condensation inside because they don't breath, but I slept pretty well.

FI Waterproof matches, butane lighter, fancy flint device... take your pick. More importantly, know how to start a fire. Most people can't start a fire with a full book of matches.

FOOD: Two cliff bars.

FLASHLIGHT: Go with a small headlamp! I've had good luck with products from Princeton Tech, Black Diamond, and Petzl. A black Diamond Storm and spare batteries are part of my standard climbing kit. For emergency use, you could go with something lighter like a Petzl Bindi (200 lumens, 35 grams).

COMMUNICATION: Garmin Inreach and cell phone.

NAVIGATION: Don't bother hauling around a compass unless you actually know how to use it. Also, don't haul around a compass, even if you know how to use it. Compass navigation is a fun skill, but it's a waste of time if you have GPS and a cell phone.

I have a Garmin InReach and cell phone. Make sure that your cell phone is prepared to navigate offline. If you have Google maps, you can download maps to the phone. I also have the Gaia app on my phone. I use Gaia for ski mountaineering but it's also useful for finding your way through the back country.

KNIFE: I keep a 1oz Gerber STL in my first aid kit. I used to be more of a knife fan, but after spending an awful lot of time outdoors, I found that I very rarely need one.

First Aid Kit: My first aid kit is about the size of a wallet. A couple band aids, ibuprofin, tweezers, a piece of mole skin, safety pin, a foot of Duct tape, etc. The most likely items I'll use? Definitely the mole skin and ibuprofin! You don't need ace bandages, trauma sheers, or a pile of gauze. Unless you happen to be naked, you should have plenty of material to wrap up a wound. As with starting a fire, you really need to know what you're doing. There are plenty of books on wilderness first aid.

CLOTHING: Cotton kills! It provides little insulation value when wet. Wear synthetic clothing and hiking shoes. I normally wear gortex trail running shoes anyways, so my feet stay dry in snow or rain.

All of my survival gear fits in my pockets (zippered pockets so I can't lose it!). Ultralight gear has gotten so good that there's no longer a need for big vests and pouches. If you really insist on carrying a couple more pounds of stuff, then check out the 986 gram Dudek paraglider. All you need to do is launch off the nearest hill and then fly home