John: In sub school at the escape trainer I was told by one of the instructors that less than .01% of the worlds' oceans are shallow enough to attempt an escape. The oceans cover 70+% of the worlds' surface. The flip side of that is that 99.99% of the worlds' oceans are deep enough to hide a submarine. Do the math and realize that covering 70% of the worlds' surface with drones is going to cost a hell of a lot more than enough Subs to be effective. Math, physics, science .... trumps everything else.