The Ten Essentials have long been described as the ten must-have items needed for safe passage during wilderness travel.

In the 1930s, the Mountaineers, a Seattle-based hiking, climbing, and conservation organization, came up with a list of 10 essential items that no climber should be without.¹

Most of these items are very applicable to casual wilderness adventures and so have become ubiquitous with different outdoor groups and the various wildnerness how-to books.

1. Map
2. Compass - (optionally supplemented with a GPS receiver)
3. Sunglasses and sunscreen - I would add a suitable hat here as well
4. Extra food and water
5. Extra clothes - minimally extra socks and a shirt
6. Headlamp/flashlight
7. First aid kit
8. Fire starter
9. Matches
10. Knife

There is a really good, complete article on Wikipedia that gets into the details of each item and its use.

Of course these are additonal items that have been suggested to add into the mix. Depending on your terrain, there may be somethings that you add in or leave out. For example, if you were traveling in the desert, you would almost assuredly want more water and not have such a strong focus on food. I almost always carry a large OD-green triangular bandage and small notepad and pen - these usually finding their way into cargo pockets or the like.

For really important items, like firestarting, it's good to follow the rule of threes - i.e. make sure you have at least three versions of that item - a lighter, matches, and a magnesium firestarter. The weight is really negligible and if you find yourself in a cold enviroment and in need a a warm fire, you'll be glad you have a back-up - or two.

Some other suggestions are:

• Two-way radio (for field-based rescue and tactical ops)
• Space blanket or poncho
• Signalling device(s) - flare, signal mirror, or whistle. I would recommend always carrying a whistle, regardless of terrain and mission type. It is one of the easiest signalling devices to use if you are injured or unable to manipulate your hands - i.e. being trapped under an ATV, etc.
• Insect repellent - honestly, this is one thing I almost never carry, as it inevitably will leak and ruin other equipment, although most of the rest of the crew will readily admit that I am myself insect repellent for them (i.e. the mosquitos leave them alone, preferring to bite me instead)
• Repair kit - specific to the types of items you are carrying - consider nylon cord, duct tape, sewing kit, etc.
• Spare ammo, cleaning kit - if traveling with a weapon (i.e. hunting)

The Texas Sierra Club has also published an article detailing a different methodology - focusing instead on ten different groupings of items and listing essentials and options in each of those categories:

The groups detailed are:

• Medical - ID/medical tag, first aid kit, medications, insect repellant
• Shelter - raingear, garbage bags, emergency blanket, bivy sack, tarp, tent, rope
• Fire - matches, lighter, sparker/tinder, fresnel lens, stove/fuel
• Hydration - water container, purification method
• Communication - safety plan, whistle, pen/pencil and paper, signal mirror, cellular phone, satellite phone, HAM radio, personal locator beacon
• Navigation - map, compass, light, altimeter, GPS
• Nutrition - extra food, fishing kit
• Insulation - jacket, hat, gloves, footwear, foam pad
• Sun Protection - sunscreen, sunglasses, wide-brimmed hat
• Tools - knife, repair kit, wristwatch, bandana

There are a lot of options and room for personal choices in the above kit lists.

The best way to find the right "basic kit" is to pack a bag with everything you think you'll need to take with you for safety in the woods. Take this bag with you on a few multi-mile hikes and keep a list of the items in the bag, putting a check next to the things you use when you get back from the trips. After a few dozen or so hikes, you'll quickly learn what you need and don't need. Remember, these need to be day-hikes, as overnights will always be encumbered by sleeping bags, sleeping pads and other items needed for noturnal comfort in the out-of-doors.

A word on batteries

The only real sure-fire way to make sure that your battery-operated kit has fresh batteries is to put new batteries into that equipment at the start of every adventure. I tend to lean on the cheap side, and so I hate to do it, but it really is the only way to make sure your batteries are going to work. I remember a search drill I went on where I grabbed my SAR chest rig (GPS, radio, knife) and headed out into the woods to get into the action. I hadn't checked my GPS since the previous drill and was bummed to find out the batteries were totally drained - the GPS having been left on since that op. I learned my lesson, but am sure I will make the same mistake again at some point.

- Many Rifles