Potomac Riverboat Co. docks at the Alexandria City Marina at Cameron and Union sts. behind the Torpedo Factory Art Center; cruises also depart from several other area locations. The Alexandria Seaport Cruise is a 40-minute round-trip sightseeing excursion. The history of the region is narrated while the boat cruises along the waterfront past historic landmarks. Other trips include the narrated 90-minute Washington by Water Monuments Cruise and George Washington's Mount Vernon by Water Cruise (includes entrance to Mount Vernon estate and a mansion tour).