Driving your submarines into a narrow area with limited depth is driving right into a bottleneck trap. It may be hard to locate a submarine out in the deep ope

Driving your submarines into a narrow area with limited depth is driving right into a bottleneck trap. It may be hard to locate a submarine out in the deep open sea, not so much if they are limited in escape routes. Some $50 microphones in the water will be able to pick up submarine activity and if the sub is in range of sending out drones it is in range of being detected by drones equipped with simple magnetic sensors. And that is assuming they can't put an active bit of sonar on two or three drones and drop them in the sea and triangulate it to within a few hundred feet to start with. That still doesn't make them easy to take out, but the cost of potentially losing a submarine is so massive that it doesn't make sense to risk them to start with.