Union Island was a merchant vessel launched at Bristol in 1794. Her master, William James Pocock, received a letter of marque for her on 6 December 1794. In November 1795 Pocock was still her master; she was described at the time as "half frigate built". Pocock remained her master until 1801. Still, a year later, in April 1802, Union Island was advertised for sale in London and described as sailing well and carrying "a remarkable large cargo for her tonnage."