The Stone Fleet consisted of a fleet of aging ships purchased in New Bedford and other New England ports, loaded with stone, and sailed south during the American Civil War by the Union Navy for use as blockships. They were to be deliberately sunk at the entrance of Charleston Harbor, South Carolina in the hope of obstructing blockade runners, then supplying Confederate interests. Although some sank along the way and others were sunk near Tybee Island, Georgia, to serve as breakwaters, wharves for the landing of Union troops, the majority were divided into two lesser fleets. One fleet was sunk to block the south channel off Morris Island, and the other to block the north channel near Rattlesnake Shoals off the present day Isle of Palms in what proved to be failed efforts to block access the main shipping channels into Charleston Harbor.

A blockship is a ship deliberately sunk to prevent a river, channel, or canal from being used as a waterway. It may either be sunk by a navy defending the waterway to prevent the ingress of attacking enemy forces, as in the case of HMS Hood at Portland Harbour in 1914; or it may be brought by enemy raiders and used to prevent the waterway from being used by the defending forces, as in the case of the three old cruisers HMS Thetis, Iphigenia and Intrepid scuttled during the Zeebrugge raid in 1918 to prevent the port from being used by the German navy.