Why has the wreck of IJN Shinano not been found?
Short answerA sufficiently funded search with the right ships and systems may not yet have been mounted.
NotesThe practical question is whether anyone is seriously searching for IJN Shinano. Finding a wreck at sea requires money, a suitable vessel, capable sensors, and enough search time. If no expedition has assembled those resources, the absence of a discovery does not itself indicate an unusual technical mystery. The exchange redirects attention from the ship's fame to the logistics of maritime search.