goTenna
It lets you text your friends in the backcountry.
Communication This Twix bar-size antenna pairs with your phone so you can text other goTenna users, even when you don’t have cell service. “It basically turns your smartphone into a texting walkie-talkie,” one tester says. Bonus: Your phone’s battery life is generally unaffected (keep it in airplane mode).
Location services The included app has built-in maps (basic, not topo). When another user sends his or her location, it shows up on the map. In most terrain, expect goTennas to have a range of 4 miles (more at altitude). In canyon-riddled terrain, their range is less than a mile. “Our group of seven split up on a trip in Colorado’s Never Summer Range, and the skiers were able to communicate with the hut-loungers,” one tester says.
Drawback In a group, goTenna is most effective when everyone has it.