It was sometime after midnight Friday, just about bedtime for Kelley Fullen, when a ding from her computer signaled that a new geocache had been hidden in the area. Still wearing pajamas, she uploaded the info to her Garmin and sped from New Albany to Campus to find it before anyone else.

It was sometime after midnight Friday, just about bedtime for Kelley Fullen, when a ding from her computer signaled that a new geocache had been hidden in the area. Still wearing pajamas, she uploaded the info to her Garmin and sped from New Albany to Campus to find it before anyone else.

In the sport of geocaching, hunters like Fullen use handheld GPS devices to search for everyday objects hidden by fellow hobbyists. They get a cache's geographic coordinates and maybe a few other clues from a website, but they never know what they'll find - or exactly where they'll find it.

"I call it geo-crack," said Fullen, known in geocaching forums as Kelinore. "I'll go out when it's four degrees outside. I'm pretty hardcore."

Eventually, under cover of night, she found her target: a small magnetic key-hider stuck beneath a metal fence. She slid back the lid, signed her name to the blank logbook and replaced the cache as she found it.

"It's addictive because no two are exactly the same," said Fullen, who enjoys being the first to find local caches posted to the global database at Geocaching.com. "There are some that frustrate you to death and others that just make you laugh."

You'll often hear about geocachers searching for buried treasure, but caches are never underground and seldom valuable. Most are small plastic containers holding little more than a logbook in a waterproof bag. You won't need to bring a shovel, and few of the contents are meant to be taken home.

In essence, you're using $100 global-positioning software and a $500 million satellite system to find Tupperware in the woods, joked Larry Cunningham, who has found more than 2,100 caches. The thrill for him is the hunt.

"It's probably the biggest hobby around that no one knows about," said Cunningham, aka LarryC43230. "Ohio is actually one of the best states for geocaching."

Though he's spent almost his entire life here, Cunningham said the sport has taken him to places he never knew existed. He's been to historic buildings, state parks and beautiful vistas in a successful quest to find a cache in every Buckeye county.

The activity has exploded across the world with cheaper, more accurate handheld technology and a cache list that grows by the hour at Geocaching.com, which also offers caching tips and message boards. As of Tuesday morning, the site listed more than 735,000 caches hidden in about 200 countries and on all seven continents.

First-timers are invited to a meeting of the Central Ohio Geocachers at 2 p.m. Saturday, Feb. 28, at Panera Bread, 6665 Perimeter Loop Rd. in Dublin.

On a trip through Campus last week, Cunningham and Fullen led me to several caches within walking distance of each other. We found a film canister stuck inside a crumbling stone wall and a small pill jar camouflaged and tied to the trunk of a pine tree. Both were considered easy on the sport's two standard rating systems: difficulty (the mental challenge) and terrain (the environment's ruggedness).

Our main goal was not to disclose the cache to "muggles," a geocaching term for ordinary folks who might spot a hidden object, not understand what's going on and steal the item. You've probably walked by a few caches without even knowing it.

More difficult finds will take you into long drainpipes, over railroad trestles and through miles of forest. Elsewhere in the world, wily geocachers have hidden them on islands accessible only by canoe and on the rim of an active volcano in Ethiopia.

"It can be as complicated or as simple as you want it to be," Fullen added. "People always talk about staycations. You could totally stay in town and try geocaching. There are about 2,600 caches in Columbus."

For more outdoor adventures and daily Nature Notes, click to The Riot Act blog at ColumbusAlive.com.