I was surprised to discover recently from a tourist brochure that there is a Russian submarine on display in Seattle. The “Cobra” operated from 1974-1994 and its missions are still classified by the Russian Navy, though there is of course speculation about where she has patrolled. Veterans of U.S. Navy submarines act as docents aboard the sub. I haven’t visited yet, but she’s docked at Pier 48. If you enjoy learning about underwater military stuff, the Naval Undersea Museum in Keyport, WA, which I have visited (and previously noted here), is full of interesting diving equipment, exhibits on the ocean environment, submarines, and the requisite weaponry of naval warfare. During the Revolutionary War, butter churns and beer kegs were filled with gunpowder for use as mines.