This is today's photo day submission, but it really belongs in this thread.

The sub is called Deep Quest, and yes it's a real sub which you can research online. It's now privately owned, and rigged to tow a PWC as a tender.

This shows the PWC.

And this shows the deck gun, which is presumably to entertain gawkers (like me). I wonder if this sub is still operationally capable of diving? (The cockpit enclosure, radar dome, and PWC rig would certainly need to be removed.)