But would they ping in on radar, that bounces off solids?

Then again, they have that thing... I don't know what to call it, where they use sound waves for tactile sensations, and even lifting objects, and they have combined that with holograms to improve user interface... Do you know this?

Also, if it's projected from submarines, does that mean we're not detecting the submarines, only their projections? That seems troubling, too...