My geocaching bag is the same bag I use for day hikes, so many of the items don't see any use while geocaching and are simply things I carry in case something goes wrong and I need to spend the night in the woods. I use a Maxpedition Jumbo Versipack, which is one of the best pieces of gear I own. For those who want the same style bag, without the cost. The UTG tactical messenger bag is a direct replica at half the price (I own this bag as well and the quality is just as good).
Hiking/Geocaching Kit:
Poncho w/ grommets to set up as a Tarp
Const. Grade Trash Bag
Paracord & Carabiners
Warm Hat
Thin Gloves
Mini First aid kit
Multi-tool
Hand Sanitizer
Gerber Slide Saw
Kershaw Echo Knife
1 watt LED Flashlight
Bandana
TP, Rubber Gloves, Hand Wipes
Rite in the Rain Notebook
Bible
Whistle
Compass & Map
Guyot Desgins Stainless Steel Water Bottle
Power Bars
Gatorade Packets
Heavy Duty Work Gloves (added grommets to hang on the bag w/ a carabiner)
Strikeforce Fire Steel & Tinder
Emergency Phone Charger
Water Treatment Tablets & 1 Quart zip lock
Water Filter Straw
Tea Bags
Sugar Packets
Watch
Garmin etrex GPS
Zip lock bag with trading items