Reddit reviews Dark Waters:: An Insider's Account of the NR-1 The Cold War's Undercover Nuclear Sub
We found 2 Reddit comments about Dark Waters:: An Insider's Account of the NR-1 The Cold War's Undercover Nuclear Sub. Here are the top ones, ranked by their Reddit score.
It seems it's NR-1.
Source. Read the comments, they seem to be unanimous in their agreement and the Wikipedia entry puts the NR-1 at 148 feet.
I'd also recommend you pick up Dark Waters - a great account of the NR-1's career and spy missions!
Good book about the NR-1.