GPS Treasure Hunting with Your iPhone 3G

9/19/08Follow @wroush

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 send you to the iPhone’s built-in Google Maps application, where you’ll see a red pushpin representing your chosen cache and a pulsating blue dot representing your current location. Keep moving until the blue dot and the red pushpin coincide, and you’ll be within a few meters of the cache.

From there, you’re on your own. Part of the fun of geocaching is that the technology only gets you so far: even the most exact consumer-grade GPS receivers can only fix a position to within two or three meters, and their accuracy drops further if the satellite signals are attenuated by trees or other obstructions. And if you’re looking for a small plastic box that might be hidden under a rock or a log, a circle 3 meters in radius can be a lot of ground to search.

GPS Kit on the iPhone 3GI batted .500 last weekend, when I took my iPhone, Geopher Lite, and my dog to Wompatuck State Park in Hingham, about 20 miles southeast of Boston. I didn’t realize it until I got there, but the park is built on the swampy grounds of a former munitions depot, where the U.S. Navy once assembled and stored nuclear depth charges and other scary items. The park is peppered with bunkers, roads, concrete pads, and other ruins that were never properly demolished after the depot was decommissioned in 1965. Which means there are lot of cool places to hide caches—there are about 30 of them within the park’s boundaries, according to the maps at

Out of the six geocaches I went looking for around Wompatuck, I located three. For enthusiasts: I found Ancient Ruins #2 [GCHT5Y], What Grade Are You? [GC15DYZ], and George Washington Forest II [GC19TND] and was stumped by Wompatuck Multi #3 [GCNEYP], Bunker N-9 [GC1DY93], and Triphammer Overlook [GCEB32]. I blame my own impatience, rather than Geopher, for my inability to find the last three caches; I guess they were just hidden too cleverly for me.

You don’t have to drive way out of town, like I did, to go geocaching. It’s a little harder, in cities, to find spots where muggles won’t accidentally come across a cache, but enthusiasts have hidden plenty of them in most major metropolises. My favorite Boston geocache so far is located near the Gillette razor factory on Fort Point Channel (The Best A Man Can Get [GCX7RV]). It’s a “microcache,” a bullet-sized capsule that contains only a tiny scroll—the logbook, where you’ll find my name in square #8. The capsule is attached by magnet to—well, on second thought, I won’t give away the secret. Another fun and easy-to-find Boston cache (Fort Point Cable Crossing [GCMVJ4], near the Children’s Museum) is the subject of an entire podcast recorded a few years ago by

If you want to go beyond geocaching and experiment with other aspects of GPS technology, there’s another excellent app at the App Store, a $9.99 program called GPS Kit, that will give your iPhone 3G many of the features of a dedicated GPSr. For instance, it shows your speed and direction of motion, has odometer and trip-meter functions, lets you save waypoints and tracks, and displays beautiful road maps and topographical maps of your current location, downloaded on the fly just like the maps in the iPhone’s Google Maps application. And unlike the very expensive maps that owners of Garmin devices and other dedicated GPS receivers must buy to make their devices work, the maps you can access using GPS Kit and other iPhone navigation apps are totally free—another huge reason why the iPhone threatens to undermine the traditional GPS industry.

Wade's GPS TrackThe track function of GPS Kit, which creates an electronic breadcrumb trail showing your movements, is particularly fun. When you’re done with a trip, GPS Kit lets you e-mail the track to yourself, and you can then view it on a Google Map or in Google Earth. At right, you can see a track I recorded using GPS Kit: it’s from my expedition last weekend to find the two Fort Point Channel caches.

TomTom, a Dutch company that specializes in automobile navigation systems, said earlier this year that it was developing an iPhone app, but there’s been no word on that front since June. Even then, the company didn’t make it clear whether its application would provide what a lot of iPhone owners have been clamoring for: audiovisual, turn-by-turn driving directions like those you can get from TomTom’s dedicated GPS devices. But I don’t think enthusiasts need to wait around to see what TomTom and the other GPS giants will do. While the iPhone doesn’t outshine the expensive, dedicated GPS devices in every detail, apps like Geopher and GPS Kit make it perfectly usable for recreational purposes—to the point that I’d question the sanity of anyone still thinking about laying down $600 or more for a handheld GPSr.

So, the next time somebody asks you what the “G” stands for in “iPhone 3G,” tell them it’s for GPS. Or better yet, geocaching.

For a full list of my columns, check out the World Wide Wade Archive. You can also subscribe to the column via RSS or e-mail.

Wade Roush is a contributing editor at Xconomy. Follow @wroush

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