Smithfield, N.C. — In a new adventure game, adults and families are combing cities, towns and the countryside. But "X" no longer marks the spot – your GPS unit does.

The activity is called geocaching. Participants organize, often in online groups, hide objects in out-of-the-way places and then search for items left by other people using GPS technology.

"You're using a multimillion-dollar satellite system to find Tupperware in the woods," said Andy Smith, a geocaching fan and self-described geek.

Participants get to keep what they find, but they must sign a log and leave something else behind in the hiding place.

"I like finding treasure. I like finding stuff," Smith said.

Smith said geocaching is fun not just for adults, but for families as well.

"The kids love treasure hunting just as much as adults do," he said.

Part of the enjoyment of geocaching is that it's year-round activity, too.

"Where else do you get to use electronic gizmos to find treasure?" Smith said.