While a decorated warship might spend its retirement as a national landmark, an underperforming vessel would be forced to make ends meet as the world’s only riverboat casino armed with antiballistic missiles. Drop anchor with today's Groupon: for $18, you get a naval-history-museum visit for two people to Patriots Point Naval & Maritime Museum in Mt. Pleasant (up to a $36 value).

Iron-clad warriors come to rest atop the waters of Patriots Point Naval & Maritime Museum, where guests patrol the decks of the USS Yorktown, marvel at 28 military aircraft and dive below the briny depths on the USS Clamagore. Retired heavy artillery and an F/A-18A Hornet fighter play shuffleboard with old landing gear upon the 888-foot Yorktown's 60-foot-high flight deck, which served as the stage for the Academy Award–winning documentary The Fighting Lady. The onboard Medal of Honor Museum honors recipients of the nation's highest award for military valor and six optional tours portray the lives of former maritime soldiers. Descending into the only preserved Guppy III submarine in the United States today introduces tourists to the 322-foot USS Clamagore, whose Cold War service included patrolling East Coast waters and accusing hammerhead sharks of being Communist sympathizers.