The Mallows Bay–Potomac River National Marine Sanctuary is a National Marine Sanctuary in the United States located in the Potomac River in Charles County, Maryland. It is best known for the "Ghost Fleet," 118 historic shipwrecks in Mallows Bay in the sanctuary's northeast corner which is the largest shipwreck fleet in the Western Hemisphere. They are among more than 200 shipwrecks in the sanctuary, some of which date as far back as the American Revolutionary War and others to the American Civil War.
In addition to shipwrecks, the sanctuary preserves historical sites related to Native Americans, some of them as much as 12,000 years old, as well as a lengthy span of United States history, including the American Revolutionary War, the American Civil War, steamboat and steamship activity during the Industrial Revolution, and what was once an important Potomac River fishing industry. It also protects sites dating as far back as the 17th century related to African-American history, as well as an ecologically and biologically important area of the Potomac River and its Maryland shoreline that supports many species of plants and animals.
