Looking for a fun, family-friendly way to exercise both mind and body? Try geocaching ("jee-oh-cash-ing"), the fast-growing sport that's akin to a modern-day treasure hunt.

Instead of a worn map marked with an X, you use a GPS receiver, a set of coordinates and (optionally) clues. And instead of hunting for a buried chest, you're looking for a cache of goodies hidden in an eco-friendly site above ground.

Geocaching Basics

What's a Cache?

How to go geocaching

Caches are hidden all over the world by fellow geocachers who put together a hodgepodge of trinkets, a logbook and pen or pencil, and perhaps a disposable camera. This hoard is then stuffed into a weatherproof box and hidden under a rock, behind a tree or maybe even in a more urban locale.

The geographical coordinates of these containers—some no bigger than a film canister—are posted on one of several Web sites for fellow geocachers to follow. One of the first and still most popular sites is geocaching.com. Check it out beforehand to find a cache near you, updates to the game, and photos and stories shared by fellow geocachers.

Caches often use a 5-star system to rate the level of difficulty and the terrain.

Basic Geocaching Guidelines

Though always evolving, geocaching does follow a few fundamental guidelines. Among them:

  • Do not place caches on private land without permission or in national parks or wilderness areas at all.
  • Do not cross private property without permission to reach a geocache
  • Do not include offensive or inflammatory material in a cache
  • Maintain a "tread softly" and Leave No Trace philosophy.

Game Variations

Groundspeak travel bug

True to its grassroots origins, the rules of the game continually morph as players originate new twists to the rules of engagement:

  1. Trinkets can include travel bugs (example shown at right) which are specific trinkets with goals attached, such as getting from New York to New Zealand.
  2. Some coordinates can be garnered only through solving ciphers.
  3. Some clues are encrypted: You can click on them to see the clue or make it more challenging by leaving them encrypted.
  4. At one time, caches could be "virtual," making it all about the thrill of the hunt rather than the reward at the end. These virtual caches are no longer permitted, having been replaced by a separate hobby of "waymarking."

Getting Started

GeoMate GPS is family friendly.

With geocaching, there are no dues to pay or clubs to join. Simply log onto geocaching.com for access to nearly 2 million cache coordinates. The game transcends geographic, political, gender and age boundaries. Geocache sites range from easy to challenging, and their level of difficulty is indicated alongside the cache's coordinates for easy access.

Geocaching and GPS units go hand in hand. Even the most basic of units is enough to track down the location of a geocache. But to get a visual acquaintance with the area you'll be searching, a map is a must. Your GPS can tell you the straight line between 2 points, but unless the route's waypoints have been preloaded into your unit, only a map can show you that squiggly path between you and your destination.

Geocaching employs the skills of problem and puzzle solving: You'll sleuth for and identify clues, learn navigation and orienteering, and you may get an introduction to other related games such as letterboxing.

Shop REI's selection of GPS receivers.

Geocaching Etiquette


The number one rule of geocaching is to follow the Golden Rule: Treat fellow geocachers the way you want to be treated.
Following geocaching etiquette ensures its survival.

REI Outdoor School instructor Steve Wood teaches the school's courses in GPS navigation and geocaching, and he is also a founding member of Geocachers of the Bay Area, a regional club with thousands of members. In this video, Steve goes over basic geocaching tenets:

  • A geocache should be placed in a way so it's unnoticeable to passers-by yet can be accessed without harming terrain or vegetation.
  • A geocache box or container should be camouflaged so it fits in with the surroundings and doesn't accidentally alarm others.
  • Don't expose the hiding spot to others. When you find a geocache, quickly move it away from the site before examining it.
  • It's good form to sign the register to let the geocache owner and fellow geocachers know of your visit. Afterwards, go online to geocaching.com to record your visit there as well.
  • Always exchange trinkets (also called "trade items") with those of equal or greater value. Leave the cache better than you found it.
  • Travel bugs are different than trade items. Sometimes called "hitchhikers," these are often intended to travel the world. They are OK to take as long as you promise to put it in another geocache. Be sure to log the travel bug number online so its owner can trace its travels.
  • Once you're done with the geocache, return it exactly where you found it. Resist the temptation to find a better or more complicated spot.

A time-honored geocaching principle is CITO, or "Cache In, Trash Out." This refers to geocachers who collect and dispose of litter found along the way. Always strive to leave the environment as pristine as, or better than, you found it. See www.cacheintrashout.org for details.

How to Play

Geocaching is simply navigating to the site of the cache by way of coordinates stored in your GPS receiver. The easiest ways to input geocache coordinates into your GPS unit are 1) Press the MARK button; or 2) Call up a previously stored waypoint, rename it, change its coordinates and save it to your GPS receiver's memory. (This creates a new waypoint while retaining the old one.)

Different GPS receivers have varying ways of calling up previously stored waypoints or changing a waypoint's coordinates. Check the owner's manual of your GPS unit for specific instructions.

The easiest coordinate system to use when entering a geocache site or waypoint is the classic latitude and longitude. This can be expressed in Degrees/Minutes/Seconds (DMS) or Degree Decimal Minutes (DDM) . The latter has quickly become the standard in geocaching. However, another coordinate system, Universal Transverse Mercator (UTM) , offers many advantages. For example, it's the easiest map-reading system. Developed by the military, UTM divides the map into square gridlines that are all 1,000 meters apart. This makes it very easy to see and judge distances. Most topo maps have the UTM gridlines printed on them. NOTE: UTM coordinates are comprised of 14 digits, 7 for what's called the "Easting" and 7 for the "Northing." If the first digit in either the Easting or Northing set is a zero, some GPS manufacturers' software (e.g., Garmin) requires you to enter the zero, while others (e.g., Magellan) do not.

Many geocache coordinates are listed in both latitude/longitude (DDM) and UTM. However, if the coordinates are only listed in one form, your GPS receiver can convert DDM to UTM or vice versa. So you can navigate using whichever coordinate system you prefer. To convert from one system to another, simply: 1) go to the SET UP menu; and 2) in the UNITS submenu, change the Position Format to either UTM or LAT/LONG, depending on your preference. The next time you open or call up a waypoint, its coordinates will be expressed in whatever system you selected.

Here's an example of how this works. Let's say that you like to use a map with the UTM grid system, but the geocache you want to find only lists its coordinates in latitude/longitude.

  • Set up your GPS receiver with the Lat/Long Position Format and record the geocache site's coordinates, name it and save it.
  • Reset your GPS unit with the UTM Position Format. When you call up your target geocache coordinates again, they'll be expressed in UTM so you'll be able to plot the location on your map.
  • Once you're in the general vicinity of the cache and are ready to begin your "on foot" search, call up the cache waypoint and press the GO TO button to help you fine-tune your search.

What to Bring

A GPS receiver, topo map and compass are mandatory items. To ensure a safe search, you should also pack the following items (and check out more advice on Understanding the Ten Essential Systems):

Flashlight: Don't underestimate the time it may take you to find the cache. Be prepared in case dusk falls sooner than you expected.

Water bottle: As with any outdoor activity, staying hydrated keeps your muscles happy and your mind sharp. Take along an ample supply.

Cell phone: Geocaching solo can be a welcome respite from the real world. But if you go alone, leave your "flight plan" with a loved one and take along a cell phone.

First-aid kit: Get familiar with your terrain before you go. Your pack should include the basics as well as items specific for the environment.

Insect repellent and sunscreen: Apply before you go and take them along to reapply along the way. You may want to consider bug-repelling and/or SPF-rated clothing.

Extra batteries: Carry spares for each electronic device you take along, such as your GPS unit and camera.

Camera: Some geocaches contain an inexpensive disposable camera. Each finder of the cache snaps a photo to record his or her success. The geocache owner, notified when the last shot is taken, posts the images online. Why not extend the spirit of geocaching and leave behind a fresh camera if the cache's camera is full?

Outerwear: Always a good idea for unexpected rain, wind and bugs.

Notebook and 2 pens: Keep a running log of all your caches. Record waypoints and coordinates for future reference. Jot down your impressions of the landscape. Take along a spare pen or pencil not just for yourself but also for the cache in case its pen has run dry.

Cache treasures: Cache finders will want to leave behind a little token (as well as take one as a souvenir). Think small, lightweight, environmentally (and culturally) friendly, inexpensive and nondegradable ideas: toy cars, tiny plastic action figures or marbles are good examples.

Pocket change: Once you have a GPS unit, geocaching is a low-cost activity. Take along a few dollars though, "just in case."

A Brief History

Geocaching offers family fun

May 5, 2000, marks the first documented mention of a GPS-directed game of hide-and-seek. On that day, Oregonian Dave Ulmer posted an open e-mail on a USENET science newsgroup calling for an activity to celebrate the United States government's taking down of satellite navigation's Selective Availability (SA).

Until this point, the accuracy of GPS receivers was limited by these partially scrambled satellite signals (SA). Remember, GPS satellite navigation was originally developed by the US Department of Defense. In the political world of spies and espionage, limiting the accuracy of GPS to those without the proper credentials and clearance made sense. In the real world of commerce and safety, however, opening up the signals for the good of all appealed to common sense.

With the elimination of SA in that spring of 2000, what once was a tracking system capable of zeroing in from space to an area the size of a football field became a locating system capable of pinpointing a spot within 2 or 3 meters.

Within a week, the first website dedicated to the collection of coordinates relating to this new activity was secured by Mike Teague. One week later, James Coburn set up the first e-mail list dedicated to the discussion of what was originally called "geostashing." That e-mail list, now on Yahoo!, is still used today. By the end of the month, the moniker had officially changed to "geocaching."

On September 2, 2000, Jeremy Irish registered the domain name www.geocaching.com and assumed Teague's cache database for the new site. Since then, numerous geocaching sites have popped up on the Web. A few of the more popular and stable sites originating from North America include navicache.com, todayscacher.com and brillig.com/geocaching/. These are where you'll find most of the geocache coordinates.

Just 10 years after Dave Ulmer's epiphanic email, more than 1 million Web-logged caches are hidden around the world. And the list keeps growing.

The Bottom Line

Geocaching is family fun

With its international appeal, worldwide internet access and minimal gear list, geocaching is an activity that is destined to stick around.

Because its function is so electronic-reliant, however, it's important for you to keep up to speed on changes and advancements that supersede yesterday's technology. (For example, did you know that geocaching currently uses WGS84 datum for all cache coordinates? Many North American maps still use NAD27. The difference between these 2 datums can result in faulty coordinates—and frustrating searches. Always check that the coordinates you enter into your GPS are WGS84-based.)

Pick up one of several books that discuss geocaching in greater detail. Get on a good e-mail list or join a reliable chatroom where you'll not only find encouragement as you develop your geocaching skills, but where you'll be able to contribute some ideas of your own.

Geocaching makes a great family activity. For tips, see the REI Expert Advice article on Geocaching with Kids.

Geocaching Q&A

For those who are new to geocaching, we asked REI Outdoor School instructor Steve Wood for some tips to get you going.

Q: How does a person find a geocache?

A: Part of the fun of geocaching is deciding how you get to a cache's location. You may know its coordinates, but you have to look at a map and choose the best way to get there. Some caches are more obvious than others. Some can be pretty tricky.

Q: Just how tricky can they get?

A: Well, I've done lots of micro-caches and frankly, I hate the ones that use little thimble-size containers. There's also a series of geocaches in the Bay Area called "terrain-challenge" caches. On a map you can see them clearly, but figuring out how to get there is a real tough navigation challenge. Maybe the best way to reach one is to use deer trails, and those can be hard to find. A lot of times a standard cache will be hidden among logs or in a pile of rocks. When I hide one and I try to think about the direction people will approach it so its location won't be obvious. Some caches give away their location, like being buried under a pile of bark that would not occur that way naturally. I've found a geocache when I wasn't looking just because I spotted a pile of suspicious-looking rocks and I decided to go take a look.

Q: What kinds of containers hold a cache?

A: For years people have preferred ammo boxes with geocache stickers. They are totally weatherproof, never degrade and are a good size. But with geocaching being a somewhat clandestine activity, the trouble with ammo boxes is that non-geocachers in parks can be easily alarmed by such things—particularly by military ammo boxes.

Q: Are any alternatives available?

A: A company called Groundspeak has come up with plastic containers with geocache stickers that REI carries. They even have a fake rock that acts as a container. People get pretty creative when making their own caches. Hollow plastic fruit has been popular in the past. People making homemade caches just need to be careful. I've heard of people using metal cylinders wrapped in camouflage tape with wires dangling from them. That's going to be questioned by non-geocachers, no doubt. I heard of one person who wanted to create a geocache that made a pun on technology, so he took an ammo box and decorated it with old circuit boards. Then he hid it under a bridge. Someone saw it, reported it and the road was closed so the box could be examined. It was done innocently, but he just didn't think through all the possibilities. Most geocachers know not to create a cache that could be mistaken for a bomb.

Q: Do most geocachers know how to play the game?

A: There are some rules and basic etiquette that most people follow:

  • Hide a cache just off a trail so non-geocachers won't notice it or be bothered by people looking for it.
  • Hide it in a way that won't disturb the environment; place it so people can look for it without doing any harm to the surrounding terrain. If a site is being damaged, the cache is pulled.
  • Camouflage it to blend in with its surroundings so it is less likely to alarm non-geocachers.
  • When you find a cache, take it away from the hiding spot to avoid exposing its location to others.
  • Hide it the same way you found it; don't make it harder for the next person to find.
  • Replace anything you take with some other trinket you bring.
  • Sign the log. Do the same online.

Q: Any geocaching tips you can share?

A: A GPS is used constantly in geocaching, but all a GPS needs to do is get you to the area where a cache is located. If it tells me I'm within 10 to 20 feet of a cache, that's all I need, because maybe the person who placed the cache used a GPS that was accurate only to 50 feet.

Once you get to the area, you've got to go back to using your brain. Take your eyes off the GPS and start looking around. Ask yourself, "What's in this area that might be a good hiding place?" A normal geocache is about the size of a lunch box or food container. So think about a log or hollow tree stump—some place that's not too sensitive.