So the submarines can't use active sonar, because their number one priority is to avoid detection... but then these subs are all parked in the same "parking spots" in the ocean. If the favored parking spots for submarines are so rare and small that collisions happen more than once, surely that undermines their stated number one priority of remaining hidden? If someone wanted to locate enemy submarines, surely they co…
How are the drones going to detect them apart from randomly running into them? Simpler approach is for an adversary to just cruise attack boats through these areas, which you would want to do anyway since once you detect them you want to sink them in wartime.
In this context the idea would be that drones can use active sonar, because they are relatively expendable.