The basic idea is to have people set up caches worldwide and share the locations of these caches on the Internet. Geocachers log onto Washington state-based Groundspeak Inc.'s Geocaching.com Web site at www.geocaching.com to view cache descriptions grouped by their location. Cache locations are expressed in longitude and latitude, and many cache descriptions contain hints using the terrain around the cache site. Caches are rated for difficulty - although the rating system is somewhat subjective, veteran geocachers say.
There are more than 1,400 caches hidden within 100 miles of Hagerstown in Maryland, Pennsylvania, Virginia and West Virginia, according to the Geocaching.com Web site.
Kochte, of Baltimore, and fellow geocaching enthusiast Jeff Walker are responsible for some of those caches. Both men say they hide caches to lure visitors to noteworthy new locations, and they seek caches, in part, to explore new places.
"It's another outdoor activity for me," says Kochte, 40, who wrote "Climbing Maryland" while working his full-time desk job entering data from the Hubble Space Telescope. "In the 50-odd geocaches I have found in the past couple of months, I've gotten to visit places, locations, areas I would never have thought to go to, never would have known existed ... And in a few caches I have found some useful items."
And by hiding caches - including one each at Black Rock and Annapolis Rocks along the Appalachian Trail, Kochte extends a tempting invitation to enjoy a healthy hike and outstanding views. Walker agrees. The survey engineer has hidden 16 caches at parks throughout Washington County to draw visitors to the area, he says.
"We have some beautiful parks in this county," says Walker, 37, of Hagerstown. "I want people to see them."
He started geocaching in January 2002 because he wanted something fun to do with his 7-year-old daughter, Ashleigh, who loves treasure hunts. Walker bought a $99 GPS receiver, logged on to www.geocaching.com, and set out with Ashleigh to find a cache hidden on South Mountain. It didn't take long for the duo to get addicted to the hobby, he says.
"It's all about the hunt," says Walker, who has found nearly 500 caches throughout the United States and in Europe. "It's very addictive."
Kochte picked up the hobby in May after a friend gave him a GPS receiver as a gift for completing his book about mountain climbing in Maryland. He has searched for more than 50 caches with his new GPS unit, which is about the size of a cell phone.
The Global Positioning System - which was designed for and is operated by the U.S. military - uses satellites that send radio signals from space. GPS receivers then convert the signals into position, velocity and time estimates. They can narrow a search to less than 30 feet, sometimes as little as six feet. GPS receivers cost between about $100 to $1,000, depending upon the complexity of the unit.
It's pretty tough to geocache without one, although some cache descriptions are detailed enough to make it possible, Kochte and Walker say.
Both men examined how other people hid caches before hiding their own. Under bridges and rocks and in hollowed trees are among the most popular caching hiding spots, they say. Walker and Kochte also looked for places not likely to be discovered by casual passers-by, and sites of natural or historical significance. Walker, for example, has hidden several caches near the Hager House in Hagerstown's City Park. The first cache he hid there was bulldozed over when city workers were clearing debris near the site, he says.
Kochte made several trips to Black Rock and Annapolis Rocks before hiding his caches because he wanted to observe activity there.