GPS Treasure Hunting with Your iPhone 3G

If you had to name the companies that stand to lose the most from Apple’s latest smartphone, released July 11, you might say Microsoft, Nokia, Motorola, Samsung, or Verizon. But I have a different list: Garmin, Magellan, and TomTom.

That’s because new third-party apps available for the iPhone 3G make it into a wholly credible GPS device, with additional features—especially, broadband Internet connectivity—that the dedicated GPS receivers available from the leading manufacturers can’t match, even at far higher prices. You’ll pay $199 or $299 for an iPhone 3G and get all of its other phone, media-player, and gaming features in the bargain, whereas handheld GPS receivers start around $250 and go all the way up to $900 or more.

Geopher on the iPhone 3GI spent last weekend getting back into an old hobby, geocaching. For all you muggles out there (that’s the sport’s term for the uninitiated), geocaching is a high-tech cross between treasure hunting and back-country bushwhacking. The object is to find small, hidden caches—usually waterproof plastic boxes holding logbooks and cheap souvenirs—using just the latitude and longitude readings on your GPS device. I wanted to see whether my iPhone, saddled up with a couple of new GPS-related programs from the iTunes App Store, would guide me to geocaches as effectively as the dedicated GPS receiver (GPSr) I used to own, a $600 Garmin GPSmap 60C.

My verdict: absolutely. If you’re looking for an outdoor activity that the whole family can enjoy, and that’s guaranteed to take you to places you never would have explored otherwise, then for about $12 you can download all the software you need to turn your iPhone 3G into a full-featured navigation device and digital compass.

If you’re planning a geocaching expedition, your first stop should always be, which lists the coordinates of some 650,000 caches on all seven continents. (On a typical day, geocachers log visits to about 60,000 of them—though I doubt the ones in Antarctica get many visitors.) The site is managed by a small Seattle company called Groundspeak, whose president, Jeremy Irish, was one of the early popularizers of geocaching about eight years ago. (In fact, the sport wasn’t even possible until May 2000, when the U.S. military relaxed restrictions on the accuracy of the satellite signals that GPS receivers use to triangulate their positions—thus allowing GPS to blossom into the hugely useful civilian navigation and recreation tool that it is today.)

Contents of a Typical GeocacheAt, you enter your current location, browse a list of caches in your neighborhood, pick one or more to visit, and record their coordinates. In the early days of the sport, geocachers would print out a cache’s Web page, head to the general vicinity, then tromp around until the coordinates shown by their GPS receivers matched those on the printout. By the time I got my GPSr in 2005, programmers at Olathe, KS-based Garmin and other companies had come up with ways to download a cache’s coordinates to your PC, and transfer the data to the handheld device via a USB connection. The caches would then show up as pushpins or “waypoints” on the device’s map display, and you could drive/hike/scramble directly to the cache by following the gadget’s built-in compass and range indicator.

But at the iTunes App Store—which, at last count, included 117 navigation-related applications—I located a $1.99 geocaching app called Geopher Lite that lets you combine the whole procedure just outlined into a couple of easy steps, without the need for a PC or, obviously, a dedicated GPSr. Geopher taps into the iPhone’s GPS chip and sends your current location to, which sends back a list of nearby caches. (Note that you need to be within range of AT&T’s 3G or Edge data networks for this part to work—so if you’re going geocaching in a data dead zone like central Idaho, you’ll need to stick to one of the old methods.)

The next step is to pick a cache and transfer its coordinates into your iPhone. This is where Geopher gets a bit clunky: because Groundspeak doesn’t allow third-party applications to grab cache coordinates from its website directly, you have to read each cache’s latitude and longitude off the Web page and type them into the iPhone by hand. But Geopher provides a nice split screen that simplifies this operation (and hey, for $1.99, what do you expect?).

From there, Geopher can do two things: show you a navigation screen that combines a compass-needle pointing toward your cache with a readout of the distance to the cache, or … Next Page »

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Wade Roush is a freelance science and technology journalist and the producer and host of the podcast Soonish. Follow @soonishpodcast

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