>SSN-589
>K-129
There sure is something fishy about these two incidences. And some former Navy Captain asked some Russian Admiral about it (pic).
https://en.wikipedia.org/wiki/K-129
For the engineering fags or those who love genius engineering feats, there's this pretty good documentary from 2010 in two parts: "Azorian: The Raising of the K-129"
After watching it I felt like that OP must've been more difficult than going to the moon.