A Geocache is a treasure hidden by high tech adventurers expressly to be found by the like minded armed with handheld GPS receivers. The Geocaching.com web site explains the sport and can point you toward stashes in your own locale. These are the caches we have created.
The official website reports, There are 16,439 geocaches near Beaverton, Oregon. And millions more around the world. Start looking. Login required. site
Try Topo Map
See Portland Confluences for which I was first to visit.