Geocaching Tuesday, September 09, 2008

A plaque marks the site of the first geocaching stash at N 45° 17.460 W 122° 24.800, near Oregon City, Ore. The original cache was hidden there by Dave Ulmer on May 3, 2000, just one day after the government disabled the selective availability system that limited the accuracy of civilian GPS units.

Geocaches are all around you. You can't see them? Probably because you don't know where to look. It helps to find the coordinates on a website like this.

So what is geocaching? You can read the full history here, but basically it's a global game of hide-and-seek. Someone hides a cache somewhere on planet Earth, and posts the coordinates on the website. Then someone else plugs those coordinates into their GPS unit and goes to find it.

About a year ago, I think, my mother sent me a surreptitious email asking what I knew about GPS units, because she thought my dad might enjoy geocaching and she wanted to get him one for Christmas. Well, she was right.

Since then, my parents have been scouring the woods and cities looking for these little hidden treasures. When my dad discovered that the very first geocache was placed about 30 miles from my apartment, it went on his list of "must-dos" when they visited last week.

[right] Alison Ginn opens up the stash at the site of the original geocache.

A typical stash consists of an ammo box or other waterproof container with a logbook for visitors to sign, and some kind of trinket to exchange. The smallest caches—"microcaches"—are just a film canister, and usually don't hold anything more than a roll of paper to sign.

Since the geocaching phenomenon exploded around the globe, several variations on the game have developed.

Some caches, for example, contain a "travel bug"—a little metal key tag with a bar code on it. Whoever finds one is supposed to take it with them, log it into the website, and then hide it in another stash. You can track its progress around the globe. (I think my parents carried three back to Ontario.)

Other caches are puzzle problems—the website doesn't reveal the actual location of the stash, but it sends you out to find clues that reveal the necessary coordinates. Once you have all of those, you know where to locate the cache.

[left] Peter and Alison Ginn read the log book from geocache no. 1 Sept. 2 near Oregon City, Ore.

When you find a cache, particularly at urban sites, you have to be on the lookout for "muggles." The term, adopted from the Harry Potter books, refers to anyone not aware of the sport of geocaching. Sometimes muggles stumble on hidden caches and take them, so you have to be a bit stealthy when you are trying to pinpoint your target in a busy area.

Today there are more than 650,000 geocaches hidden around the globe, and tens of thousands of people looking for them.