The Seamen's Union of Australia (SUA) was the principal trade union for merchant seamen in Australia from 1876 to 1991. The SUA developed a reputation as one of the most militant trade unions in Australia and was closely associated with the communist movement in Australia. The SUA merged in 1993 with the Waterside Workers' Federation to become the Maritime Union of Australia (MUA).

The Waterside Workers' Federation of Australia (WWF) was an Australian trade union that existed from 1902 to 1993. After a period of negotiations between other Australian maritime unions, it was federated in 1902 and first federally registered in 1907; its first general president was Billy Hughes.