Been there done that in old diesel subs 45+ years ago...going into New London.
you mean
ROTTEN GROTON ?
We were sailing in the same general area, another time. A mile or so off the coast. I was usually at the helm (DH was usually plotting courses) and I always had a chart in my hands. (We sailed, with the family, for about two week stretches) I always wanted to know exactly where we were, where the next buoy was and all that. I noticed a very very small island, off in the distance, that was NOT on the charts! I could see what appeared to be a short dark structure on it, and waves breaking on a shore just below the structure. We were really puzzled! Then the whole thing turned and we realized it was a sub when we saw the diving planes/?fins? on the side of the tower!! LOLOL! Puzzle solved!