The slave ship Mary left the African coast carrying enslaved Africans toward Dominica. About 308 people had been taken aboard.

Vessel: Mary; flag: Great Britain; rig: Ship; estimated standardized tonnage: 185. People recorded in connection with the voyage: Investor: Harper, William; Investor: Brade, Robert; Captain: Hornby, Charles. The voyage began at Liverpool on 11 June 1791. Principal recorded place where captives were acquired: New Calabar (Bight of Biafra and Gulf of Guinea islands). Principal recorded disembarkation place: Dominica, place unspecified. Estimated mortality during the crossing: 5.0%. Recorded outcome: Voyage completed as intended.