[Pay08]

The problem is that it's to my knowledge very difficult to know where maritime mines are, since they get swept around by currents.

[bigyabai]

CAPTOR is your solution: https://en.wikipedia.org/wiki/Mark_60_CAPTOR

$130,000 a pop in 1980s money, probably even cheaper if you have trade inroads with China and a bunch of 533mm torpedos sitting around in storage.