The slave ship Neptune arrived with enslaved Africans in Uruguay. About 357 people had been taken aboard and approximately 349 arrived.

Vessel: Neptune; flag: Great Britain; rig: Ship; estimated standardized tonnage: 343. People recorded in connection with the voyage: Investor: Bolton, John; Captain: Phillips, James. The voyage began at Liverpool on 21 July 1803. Principal recorded place where captives were acquired: Bonny (Bight of Biafra and Gulf of Guinea islands). Principal recorded disembarkation place: Montevideo. Estimated mortality during the crossing: 2.2%. Recorded resistance: Revolt by enslaved people. Recorded outcome: Captured by Dutch - after embarkation of enslaved people.