STERLING - It all started in 2000, when a GPS enthusiast hid a black bucket in the woods outside Portland, Ore. and posted its coordinates on a science Web site. Now, more than 870,000 such treasures on all seven continents are strapped beneath city park benches, tucked inside tree hollows and lodged between stones in lake bottoms. And nearly 100,000 people are looking for them.

Some might write it off as another example of technology mucking-up the good-old days, when a walking stick and an imagination were enough to entertain. But geocaching - GPS-led treasure hunting - has become a phenomenon that participants say has motivated them to get outside, exercise and explore new places more often.

“It's a way to use the technology to go searching for things,” said Sterling Nature Center Director Jim D'Angelo, who led an introduction to geocaching class at the center Saturday.

Geocaching goes like this: Someone hides a cache - ammo boxes, Tupperware containers and film canisters work well for keeping trinkets and visitor logs dry - and posts its coordinates on the geocaching Web site (geocaching.com). On the site, geocachers can search for cache locations by entering an area code or town name.

The only tools needed are Internet access and a global positioning system, but water, snacks and good walking shoes are good ideas.

With the aide of a GPS, geocachers navigate the forest, city neighborhood, or desert - caches are hidden all over the world - to find the cache. When found, visitors sign the log, and later record their trip on the Web site.

More than 1,200 caches are hidden within a 30-mile radius of Auburn, eight of which are at the Sterling Nature Center.

At the introduction class Saturday, geocaching greenhorns learned the basics of the hunt - be stealthy when in populated areas, do not disturb natural habitats when in the woods, replace any trinket taken from a cache, always bring extra batteries - and put their new skills to practice.

“I'm pretty good with maps,” said Regina Setikas, of Fair Haven, as she wandered around the nature center, GPS in hand. “But - where the heck am I?”

Setikas and the other beginners soon located the Hershey's cocoa tin D'Angelo had hidden for practice. This was Setikas's first hunt, but she plans to purchase a GPS, which cost as little as $80, and look up caches in the Adirondacks, where she likes to hike.

“It just adds another level of excitement to hiking and traveling,” said Setikas.

With so many to choose from, Setikas will be able to select hunts that fit her appreciation of cool weather and intolerance for heavily-wooded, poison ivy-filled environments, she said. “It's just a nice activity to do in a non-threatening, noncompetitive way.”

“It's a game. It's a competition,” said Lisa Lopez, at a geocaching get-together for experienced adventurers, which followed the beginners class at the nature center.

Within two years, Lopez has found more than 2,100 caches.

“I've done all of Fulton, cleared Cortland,” said Lopez, of Manlius. She has gotten as far west as Auburn, and is chipping away at Oswego and Ithaca. Friday morning, she got up at 5 a.m. with the intent of heading out to some new caches in Cortland - being the first to find a cache, FTF to those in the know, is a matter of pride and a goal Lopez strives for - but never left home because the geocaching Web site showed that someone had beat her to it.

When she and her family leave for a trip to Alaska, they will stop in Seattle to knock off two of the three “big ones” for geocachers - one in the geocaching headquarters and one of the last remaining Planet of the Apes caches, which is filled with paraphernalia from the movie.

The third cache in the trifecta is the original, buried in the Oregonian wilderness, which Lopez will not find this trip, she said. “Another time.”

Staff writer Sarah Gantz can be reached at 253-5311 ext. 237 or sarah.gantz@lee.net