https://m.youtube.com/watch?v=CVYNOrFK3B4
The above link is a doc on underwater sub/event tracking using acoustics. Only a week to sort out an event in the vast oceans is still amazing after Craven did it in 1968 using research hydrophones to find Scorpion. Good companion book is Blind Man’s Bluff which details the sub events of the 60’s and on.