Vast indeed...look at the case of USS Indianapolis. If they hadn't happened upon that log from the LST, which gave an entirely new possible last position, then they might never have found her.
I'm surprised they never found the Soryu or Hiryu. I mean, the Soryu was lost right around the same area as the Akagi and Kaga. While the Hiryu did move away from the other three after they were hit. What about Hammann ? She was right near Yorktown when she was sunk. I'm stunned this survey didn't ...