[ak_111]

Exactly this, "imploded straightaway" doesn't explain no implosion registered AND probable banging noise heard a few days later, so it doesn't explain everything.

"Lost then imploded" explains both by adding only a small extra assumption so by occam's razor is strictly superior to imploded straightaway as far as I can see.

[jandrese]

People are putting a lot of weight on the whole "one vessel heard a rhythmic sound while exploring". From what I've seen of these investigations the ocean is a noisy place and sometimes it gets mistaken for signal. We saw a lot of similar reports from the MH370 investigation.

My money is on simple catastrophic failure of the hull and it not being detected either because the private company is run by jokers who weren't listening for it or because they have been running around like chickens with their heads cut off because the CEO and paying customers just died and they don't want to have to report that to the family, government, media, insurance company, etc... Either explanation is plausible, but I'm slightly more inclined to go with the second simply because they were actively trying to communicate with the sub when it happened and it seems so improbable that they could miss it.

[tapland]

If you ignore ballast failures and want it to be that way, sure