It would be quite interesting if they were using a suicide submarine as a delivery system for a crude nuclear device in San Francisco Bay.
All sorts of alternate history stories could be written from this point.
the hulk of a big, powerful Japanese sub sent on a desperate mission to destroy San Francisco in the last days of World War II.
Hmmm, I wonder why they were interested in San Francisco rather than a really important target like Newport Beach or Malibu. Like anyone would even notice an attack on San Francisco.