All that I really need to go geocaching is my GPSr and a pencil, but I often take a little more that I carry in a small pocket-size bag. It has mostly everything I need for any geocaching adventure, whether it is a walk through a local park or up a mountain trail.
My Geocaching Bag -
This is my (updated) "take to every cache" geocaching bag. Nothing special, nothing fancy; just a plain canvas zipper bag with an official geocaching.com patch sewn to its front.
There are two things that I really like about this bag:
1) It is small enough to fit into a pocket.
2) It has everything I need to go geocaching.
The Inside Goods
Inside my geocaching bag, I carry:
1) Ball-point Pen and Pencil - I strictly adhere to the tenant that a traditional, mystery/puzzle, event, or multi-cache is not officially found unless I sign the logbook. Therefore, I always make certain I have at least two ways to scratch my mark. Ball-points tend to write on all types of paper, even when wet, and a backup pencil works in the colder weather I experience for a good portion of the year.
2) Extra Log-Sheets - Again, unless the logbook is signed, I don't consider finding a geocache legitimate as a "Found it" cache, so I bring a few extra logsheets in common sizes along just in case I run into one that is just too full to fit my signature or needs to be replaced.
3) Signature Items - I have gotten away from leaving pathtags in geocaches and instead have had made half-size business cards with my geocaching name and special trackable code that I leave in geocaches that I really like, or feel are a great example of what I feel is a true high-quality geocache.
4) Garmin Foretrex 101 - A super-basic GPSr, but it has been with me since the beginning and has led me to every geocache I have ever found.
5) Extra Batteries (not shown) - The Foretrex101 must be fed.
6) Mini FTF Geocoin - I like to snap a photo of the geocache along with this mini geocoin when I am fortunate enough to claim a First-to-Find.
7) Metal Pencil Sharpener (not shown) - Sometimes I come across geocaches that need their resident writing utensil sharpened in order to actually function. Metal is much more durable than plastic (and this was originally a trade item that happened to just stay in my bag.)
8) "Hooked" Safety Pin - Most of my items are self-explanatory -- except the safety pin. I heard about these neat little tools from Sonny on the PodCacher podcast. It is simply a basic safety pin with its tip bent slightly with a pair of pliers. Closed, it just hangs out attached to the side of my bag, but when I come across a very snug micro- or nano-cache, the pin can be opened, inserted through the center of the rolled-up logsheet, "hook" the bottom edge, and pulled up with the whole piece of paper to sign.
9) Notebooks & Virtual Patch - I use these notebooks to answer questions required of most Virtual and EarthCaches, as well as to take other useful notes, solve puzzles, or sometimes even replace a soggy, missing, or full logsheet. I had the patch made for holding up while I snap a picture of myself at Virtual geocaches.
Tools of the Trade (TOTT)
As a fairly experienced geocacher, I have learned to read through geocache descriptions thoroughly, look through previous find entries, and make educated guesses as to whether or not a TOTT may be necessary to retrieve a geocache. As such, I have collected a few items I have found to be very handy for this particular job. A dental mirror helps to see into areas I would otherwise be unable to (such as under a bench, or other metal object). An extenable magnet helps to reach those smaller geocaches that have been placed inside tubes or just out of reach. An ultraviolet (UV) light is used to read "hidden" messages written with a special UV marker.
For longer adventures, I take my regular daypack with all the typical items required for a safe and comfortable hike (including my trusty bear spray). Some items include:
1) Cell-Phone - I don't often have service, but it's good to have along anyway.
2) Water Bottle - Although the best place to carry your water is in your belly!
3) Bandana - There are dozens of uses for this, it would seem impractical not to carry it.
4) Leatherman - This item is rarely used, but there are lots of tools available just in case.
5) Lighter - One of the few "survival" items that I always carry.
6) Notebook - I like to write and make sketches of my adventures, plus I always have an extra logsheet.
7) Rain Poncho & Emergency Blanket - Again, "survival" items, but they make getting caught in the rain a little less miserable.
8) 120-Decibel Whistle - Because I often geocache by myself, I carry this item just in case I fall and need to signal for help. (Fortunately, this item has never needed to be used!)
9) Sunscreen & Lip Balm - The sun and wind are harsh in Montana - it pays to use preventative medicine rather than reactionary.
10) First-Aid Kit - Very simple. I cannot perform surgery with it, but I can clean a wound (alcohol wipes), keep the wound from getting infected (antibiotic cream), cover it (super-tough cloth band-aids), and help alleviate the pain (ibuprofen). I also have tweezers for removing pesky thorns, ticks and splinters.
11) Compass & Map - "Never rely on technology!" That was my mantra while in Army basic training, so it is habit that I always carry a compass. I also make a basic topo map of the area I am going to be in using google maps and window's paint program.
12) Tissue Paper & Zip-lock Baggie - For if nature calls.
13) Hard Candy & Trail Snack - I find that hiking always makes my blood-sugar level drop so sucking on a piece of hard candy helps. And who doesn't enjoy a little trail-mix or granola bar after a successful cache find?
14) Geocaching Bag - This has everything else essential to my geocaching adventures (see first entry).
And that's about all I carry. Sometimes, I will carry a walking stick, and if the situation demands it, I will bring other necessary items, such as cross-country skis, snowshoes, my inflatable kayak, or even a ladder!