Meet the PackLite Max Phone Charger: an inflatable lantern and phone charger designed to get you out of trouble in the outdoors. It charges your phone through its 5V/2.4AMP USB output port. The lantern provides you with 150-lumen output and packs flat to 1″ thick.
The lantern is waterproof and can be submerged up to 1 meter deep. You can charge it by micro USB or its solar panel. This is available for as low as $35.[where to get it]