The Ten Essentials

1. Map
2. Compass (optionally supplemented with a GPS receiver)
3. Sunglasses and sunscreen
4. Extra food
5. Extra water
6. Extra clothes
7. Headlamp / flashlight
8. First aid kit
9. Fire starter (matches, chemical heat tabs, canned heat, or a magnesium stick)
10. Knife

Additional desirable items

1. Signaling devices - such as a whistle, cell phone, two-way radio, satellite phone, unbreakable signal mirror or flare
2. Repair kit - including duct tape, bailing wire, spare binding screws and basic sewing materials
3. Waterproof tarp (or two large plastic garbage bags) and rope - for expedient field shelter