Interior navigation is only just coming into its own, but IndoorAtlas has developed a technology that could make it just as natural as breathing -- or at least, firing up a smartphone's mapping software. Developed by a team at Finland's University of Oulu, the method relies on identifying the unique geomagnetic field of every location on Earth to get positioning through a mobile device. It's not just accurate, to less than 6.6 feet, but can work without help from wireless signals and at depths that would scare off mere mortal technologies: IndoorAtlas has already conducted tests in a mine 4,593 feet deep. Geomagnetic location-finding is already available through an Android API, with hints of more platforms in the future. It will still need some tender loving care from app developers before we're using our smartphones to navigate through the grocery store as well as IndoorAtlas does in a video after the break.