"Anybody who wants to get outdoors would love to do it. If I'm driving down the street, I know and see something that other people don't," Doug Mowen said.
Mowen, of Waynesboro, Pa., started geocaching last Christmas and has since found 2,000 caches.
Mowen visits www.geocaching.com to research caches in the area. Using clues and GPS coordinates, he sets off to find the caches that are sometimes as small as film canisters and pill bottles.
Mowen attempted to find his first cache at Renfrew Park in Waynesboro.
"I struggled, and I was lucky because I met up with two other people caching. They showed me the ropes," he said.
Caches, which are hidden by proponents of the game, are supposed to have logbooks for visitors, according to the geocaching Web site.
They also can have trinkets, and participants are supposed to leave something of their own if they take something, the Web site stated.
Pollard has put trading cards in her caches, which are old-fashioned milk boxes.
"The goal of these was to promote our historic sites, and hopefully we'll be able to have more expansive participation with the (spring) season," Pollard said.
Some of Triada Chavis's favorite caches are those that provide history lessons.
Chavis has "virtual caches" at Gettysburg, Pa., among the more than 200 she has found since 2004.
"Some of these caches are right out in the open. If you don't know about it, you walk by it every day," said Chavis, of Waynesboro.
Her first geocache excursion was to Hecht's, now Macy's at Valley Mall.
"I was like, 'Oh my God, this is so much fun!' For me, it's the hunt, searching and trying to get the coordinates down," she said.
Pollard lists her caches on the visitors bureau's Web site at explorefranklincountypa.com. She includes clues, so users don't necessarily need a GPS to find those.
Potter and his family did their first caches without a GPS, using clues from geocaching.com. The Potters now use a handheld GPS and have just three caches remaining undiscovered in Washington County.
Larry Potter said, on his last check, 100 caches were hidden within a three-mile radius of downtown Hagerstown.
"Worldwide, there are between 450,000 and 500,000," Potter said.
The Hagerstown man hides caches and keeps his 6-year-old daughter and 12-year-old son in mind when doing so.
"We try to put kid-friendly stuff in them," Potter said. "You can use just about anything as a container."
"I use billion-dollar military satellites to hunt for Tupperware in the woods," Larry Potter's wife, Tina, said, quoting a common geocaching phrase.
Tina Potter praised geocaching as a way to get children outside and active.
If Mowen is looking for a cache in a public place, he'll sometimes try to involve children and parents in the area.
"You can take children on this, and it's a game for them," Mowen said.
"The whole family can be involved," Chavis said.
Alex Potter said one of his favorite activities is the annual hunt for Cache Across Maryland, which requires cachers to collect clues at 10 sites.
"In order to find out where the picnic is being held, you have to travel around the state and find coordinates," Larry Potter said.