'Planet' Quest

By its very name, the Global Positioning System (GPS), a constellation of 24 satellites that can pinpoint your exact location on Planet Earth, suggests a grand adventure. But unless you're trekking through the jungle like astronaut Leo Davidson (Mark Wahlberg) in ''Planet of the Apes,'' or lost in a rental car, GPS is pretty useless. That's beginning to change: In May 2000, 55-year-old Dave Ulmer hid a bucket filled with CDs, a can of beans, and a logbook outside Portland, Ore., and posted the coordinates to a Usenet newsgroup. Since most GPS devices are accurate only up to a 30-foot radius, finding Ulmer's half-buried treasure posed a challenge. But three days later, the booty was discovered and two intrepid Netizens noted their visits in the logbook -- and online. Thus was born the 21st-century scavenger sport known as Geocaching, which includes more than 3,000 caches hidden in all 50 states, as well as in at least 59 other countries. The game's official atlas is Geocaching.com, a website at which new coordinates get posted and hunters exchange stories. Garmin, a company that makes GPS devices for consumers, estimates that 30,000 to 50,000 people are playing along.

In June, Twentieth Century Fox upped the ante by stashing props from ''Planet of the Apes'' in 14 locations around the world and working with Geocaching.com to announce the coordinates. The first container, planted near San Francisco, held a wooden spoon that could fetch as much as $1,000 from a collector, according to Fox. The second, coincidentally captured by Ulmer himself outside Portland, included one of the clubs wielded by the film's simian rulers. The last of the ''Project A.P.E.'' coordinates will be announced Aug. 10, nearly two weeks after the film's opening. But even if you miss out on the prized collectibles, Fox is adding new goodies to its caches periodically. Here are some tips to help you start monkeying around with Geocaching: