Find yourself on the trail--literally
The GPS chip inside your iPhone is darned good, able to pinpoint your location to within 30 feet or so--that's on par with dedicated GPS devices. Pair it with an app like MotionX GPS and you've got a GPS receiver on par with dedicated devices that cost hundreds of dollars. Plus, you can download the maps ahead of time so they're on your device when you need them, even when you don't have a cell signal. You can set major waypoints in advance, and then add more on the fly once you get there, marking locations like a hard-to-find waterfall, your campsite, the trailhead--even where you parked your car. If you add a $1 app called Beacon, your iPhone's GPS radio can even help others find you in an emergency.
GPS can be used for fun too. Download the Geocaching app and you can join the large and growing movement of "high tech treasure hunters." The app shows you caches in your area and helps guide you to them and rewards your efforts with the chance to sign a logbook, trade trinkets with your fellow cachers and of course, spend time with nature. Just watch out for the muggles.
Or find your place in the universe
Some of the best apps that came out early days of the app store were astronomy apps, and they've only gotten better since then. Star Walk 2 is a longtime favorite that not only shows you the stars and planets, but follows your gaze to make it easier to identify what you're seeing. And with frequent updates, it tracks things like comets, satellites, and the International Space Station.
Is that poisonous There's an app for that
Lots of great reference apps can help you out on the trail. iBird Pro, the Red Cross, and Audubon offer tremendously useful reference apps that you can take with you without adding a single ounce to the weight of your backpack.
They can help you identify trees, plants, birds and other flora and fauna you may encounter in your adventuresbut they can also offer you practical advice for emergency situations. Please, please don't rely solely on this information as a substitute for a working knowledge of first aid. But remember it can be absolutely critical backup information in a lifesaving situation.
Unleash your inner Ansel Adams
Try as I might to prove otherwise, there's almost no way to take a bad nature photograph. And as its camera continues to improve, the iPhone has earned its place in your backpack for its photographic value alone.
The panorama feature in newer iPhones is perfect for capturing the expanse of a mountaintop vista or the surf coming in on a sun-washed beach. A lens kit can provide great new perspectives, like a wide angle view from your kayak or a close-up macro shot of a unique flower or friendly bug. We like the 4-in1 lens and the compact Macro 3-in1 set from Olloclip, and the wide-angle and telephoto lenses from Moment and ExoLens. Put yourself in the picture using Joby's GorillaPod and your iPhone's timed shutter feature.
Keeping it charged is easier than ever
So now that you have some reasons to bring your iPhone with you into the great outdoors, let's be sure it's usable once you're out there.
Let's start with what not to use. While they may have their place in general use, solar charger cases generally aren't a great solution for the trail. Unless you're wearing your iPhone on a lanyard or strapping it to your backpack, it's probably going to be spending most of its time in your pocket. I don't know about you, but my pocket generally gets very little sunlight. And even if it did, the small panels on iPhone cases can gather precious little light to turn into power.
The simplest solution for getting more power on the trail is to bring more power with you, in the form of an external battery or two. For most full-day or even weekend excursions, a separate battery pack will get you through your trip. An external battery that supplies 1,800 or more milliamp-hours will keep you charged even while using your iPhone as a navigation aid or reference source, and you can find good ones for $15 or so these days.
For longer trips, focus on recharging your external batteries rather than the phone itself. That's because using your iPhone is a whole lot easier if it's not connected to a charger. Also, iPhones tend to be finicky about how they're getting their charge. Solar chargers and other direct charging methods tend to be a little volatile in the charge they deliver, which means you might get a lot of "This accessory is not supported..." messages. By charging the battery first and using the battery to in turn charge the iPhone, you'll tend to get a more stable supply of energy. (This method also has the nice benefit of letting you use your phone on the trail while your battery charges undisturbed back at camp.)
If you really need a way to charge in the field, there are a few ways to do it. Dedicated solar chargers, like those from GoalZero are the most traditional method, and solar technology has improved by leaps and bounds in the last several years. Solpro's Helios Smart is a 5000mAh external battery with attached solar panels, so you can charge it up with USB before you leave and then recharge it with the sun.
Thermoelectric chargers convert heat into electricity. (That's oversimplified, but essentially correct.) The Biolite stove does it from the stove itself, while PowerPractical's The PowerPot does it using a specialized pot. I prefer the PowerPot's approach, since it lets me choose my own heat source, but each has its fans.
Finally, myFC offers PowerTrekk, an external battery that generates electricity by removing the hydrogen atoms from water. (Another oversimplification.) Using a silica-based catalyst, it can deliver about an iPhone's charge, with a removable "puck" and two tablespoons of water.
Expect to pay between $100 and $150 for any of these charging solutions, and remember that as with most decisions about what to add to your pack, chargers and/or extra batteries are a compromise between convenience and weight.
If it ain't broke, keep it that way
Cases are non-negotiable in the wild. Choose one with a "military grade" rating. This means is undergone rigorous testing for things like falling, wind and water. OtterBox and Lifeproof are probably the best-known names here, but there are great options from Griffin, Trident, and others. Look for cases with built-in screen protectors, dual-layer construction and a design that recesses the screenit'll put some space between your screen and whatever it lands on. There are cases that support TouchID, but I find them a little wonky. I'd rather either turn my passphrase off for the duration of the trip, or use a simple four-digit passcode. That's a personal decision, of course, but I find it far less frustrating.
If your adventure involves time in the water, swap out that rugged case for one that's waterproof. Waterproof cases from companies like Optrix and Hitcase even include add-on lenses that are great for underwater photography. (Note that there's a difference between water resistant and waterproof. Being certified as waterproof involves a different rating. Unless a case specifically says it's waterproof, it's not.)
Happy trails to you
We've just scratched the surface of what you can do with your iPhone in the great outdoors. Whether it's on the trail, at camp, on a bike or a boat, the time when high technology is viewed as a detriment to high adventure is over. Add your best "Tech vs. Wild" stories and ideas in the comments.