[the Batfish sank 15 Japanese vessels during the war, among them three submarines in just 76 hours]
Wow
The three imperial vessels / subs sank in a bit over three days in 1945, I’d guess (without looking it up) took place during the Battle of Okinawa, which was one of the biggest battles in history, and a lot of ships went down, including the Japanese suicide ships, the Japanese’ (and history’s) largest battleship, and more.
related topic:
http://www.freerepublic.com/focus/bloggers/3751788/posts
Some or all of those subs had radar, looking for Allied ships, but also broadcasting “I’m here! Come and get me!”, which the Batfish did.