Knowing where you are is very much the problem. If you are 100 meters east of where you think you are, the sea mount you think you are 100 meters west of is a b

Knowing where you are is very much the problem. If you are 100 meters east of where you think you are, the sea mount you think you are 100 meters west of is a big problem. Inertial navigation systems tell you your position relative to your last "known" location, but if that last point was inaccurate, or if too much error has accumulated since the last point, you can be significantly off from where you think you are. Couple this with the lack of good maps of certain sections of the sea floor, and human error, and a collision every couple of years becomes probable.