The Russian Submarine Museum consists of an actual nuclear submarine and a trailer of exhibits docked near downtown Providence. You will see small signs directing you to it from various spots in the downtown area. If you do not see one of the volunteer guides at the dock when you arrive to the sub tour, it is worth your while to wait a few minutes as they are probably completing a prior tour. Also, take the time to view the exhibits in the trailer and talk to the staff there, as the story of how the sub got to Providence is interesting in and of itself.