The Ten ESSENTIALS for any outdoor activity:

   1. Map
   2. Compass
   3. Sunglasses and sunscreen
   4. Extra clothing
   5. Headlamp/flashlight
   6. First-aid supplies
   7. Firestarter
   8. Matches
   9. Knife
  10. Extra food

Details:  http://www.rei.com/expertadvice/articles/ten+essentials.html