GPS Technology Drives Global Treasure Hunt

Brian Handwerk
for National Geographic News
December 1, 2004
The key to hidden treasure lies in your handheld GPS (global positioning
system) unit. GPS-based "geocaching" is a high-tech sport being played
by thousands of people across the globe.

To the uninitiated, the sight of people circling methodically around a local woodland or city park, GPS device in hand, is a bit puzzling. But this strange behavior has a purpose: They're people in search of a hidden a cache—one of tens of thousands of hidden treasures planted by other players.

"I go out with my five-year-old and nine-year-old as a family," said geocacher Rich Ness, assistant manager of Bloomington, Minnesota's REI outdoor-gear store (GPS coordinates: latitude 44° 51.6' N, longitude 93° 17.3' W). "I haven't come across a kid yet who didn't think it's the greatest thing ever."

Adults are hooked too.

Interested? There's a cache near you. In fact you might be amazed at just how many caches are near you.

But just what is a cache? The answer is as different as the people who hide them.

The cache, often a piece of Tupperware, might contain only a logbook with some amusing stories of geocaching adventure. Others are stocked with prizes like books, software, CDs, videos, money, or toys. (Food is frowned upon, as are such restricted items as alcohol and fireworks.)

Cache hiders use one of several Internet hosting sites to publish and share the coordinates of their clue sites, or waypoint (see the related links at the bottom of this page for site details). Players choose a target, then set off with handheld GPS units—using the technology to locate a variety of hidden booty.

"People have gotten very creative," said Quinn George Stone, a resident of Rochester, New York, and a founder of hosting site "The first coordinates might take you to a monument or a gravestone with dates on it, where you might have to do some mathematical equations to get the next set of coordinates. Some caches actually have 30 to 40 waypoints before you get to the container."

A few basic rules apply when one successfully finds a cache: Take something from it, leave something in it, and fill out the logbook to document your adventure.

GPS-Driven Outdoor Adventure

It may sound easy to follow a GPS unit to known coordinates, but getting there is not always so simple.

Caches could be hidden on sheer cliffs, requiring climbing gear, or found in the underwater realm of scuba divers. Urban caches are stashed inside and outside buildings. While most caches are located in far more conventional locales and require only walking, your GPS device will only take you so far before your brain must take over.

"It's a lot of fun, and if the GPS units were more accurate, it wouldn't be as much fun," geocacher Ed Hall said. "GPS gets you within 20 feet (6 meters), but then you turn it off and start looking under logs and behind bushes to find who knows what."

Hall's Colorado-based Buxley's Geocaching Waypoint Web site features roughly 1,500 maps that display where caches can be found around the globe.

It's not known if former U.S. President Bill Clinton has attempted geocaching, but his administration gave the sport its start by ending GPS Selective Availability (SA) on May 1, 2000. SA was a degradation feature that limited the accuracy of civilian-owned GPS units to one-tenth their capability.

Today GPS devices are widely available and increasingly popular among boaters, hikers, and other outdoor enthusiasts. Units range in price from U.S. $100 to $1,000.

Here's how GPS works: Satellites broadcast their current positions by radio frequencies. A handheld unit reads this information from multiple satellites, and uses triangulation to determine its (and its user's) actual position to within 6 to 20 feet (2 to 6 meters).

"Geocaching has helped introduce GPS technology to the masses and to reach a younger audience," said Pete Brumbaugh, a spokesperson for Garmin, a leading manufacturer of handheld GPS devices. "There are schools that use geocaching to teach geography, to meld technology and the outdoors together," he said from Garmin's Olathe, Kansas, headquarters.

Mike McCarty, REI's product manager for navigation and communication, has seen geocaching influence GPS-device demand at the outdoor retail giant. "People are definitely buying them for geocaching," he said. "The fact that Garmin and Magellan are building geocaching features into their units points to that."

Precautions Are Necessary

Common sense guidelines keep the activity fun—and safe. They include basic wilderness knowledge, such as always letting someone know where you're going, and other precautions specific to geocaching.

"We're very strict about telling people, Don't place a cache under a [highway or train] bridge, with all that's going on in the world," Stone explained.

Geocachers have drawn unwanted official attention in locations such as airports, where their GPS reconnaissance has raised some eyebrows.

As with many an outdoor activity, access is an issue. Caches should be placed on public property where permission is granted. Placing a cache on lands administered by the National Park Service (NPS), for example, is illegal without express permission.

Where access is granted, geocachers seek to maintain low impact by avoiding burying caches or leaving them visible to other visitors.

The thrill of the hunt draws all types. Stone has found his New York-area geocachers to be in their early to middle 50s on average, and he sees many families with young children as well.

"We had a lady who's 84 come to our last picnic cache," he said, referring to a geocachers meet-and-greet organized by—what else?—posting coordinates online. "She's a retired teacher and was going after a cache called Troll's Treasure. The only way to see it was to look through the slats of a small footbridge. She'd lie down on this footbridge but joggers kept coming along and helping her back up. She had to finally give up and come back in the evening when no one was around."

REI's Ness, who's seen increased interest in geocaching at his store, sees a common bond that transcends age or occupation.

"Most people just like to be outdoors," he said. "This is a reason to go for a hike or a walk or go to and find that new park somewhere."

Indeed, geocaching has been one of the best tour guides Ed Hall has ever consulted.

"People tend to put caches in beautiful places that they've visited," he said. "My boys and I geocache when traveling, and locals have directed us to some of the most beautiful spots around the country that we never would have found."

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