I did a Yahoo search with "soviet submarine k-129" and that came up with some stuff. Interesting research. The "official" story of the K-129 mimics what happened on the sub I was on, but we managed to recover obviously. Most likely cause of the loss was their weapons. Some Soviet torpedo's were notorious for blowing up (see Kursk). Could have been the vertical missiles they were carrying. Those were less than reliable as well. The Soviet Union often cut costs and safety on submarines, more than other programs, and with disastrous results.