During a recent crossing of the Strait of Juan de Fuca, we noticed something heading towards us from about a mile away.  From that distance we could see 2 large vessels with something smaller between them.  There also was a medium size vessel in front of and behind them.  None of these 5 vessels showed up on our AIS system.  As we got closer, we realized it was a US Navy Submarine flanked by Navy ships and a coast guard vessel in front. The sub’s tower and only about 10′ of the hull were visible.  They were headed west and we passed at a distance of about 1/2 mile going east.  The picture on the left was taken as they passed us and you can see the sub tower just in front of nearest flank vessel.  The one on the right was taken about a half mile after they passed us, but still within torpedo range!