The ITF is a global federation of transport workers' unions, representing around 20 million workers in 147 countries. It works to improve conditions for seafarers and ensure fair treatment across the maritime industry.

The SIU represents mariners, fishermen and boatmen working aboard vessels of all types in the deep sea, Great Lakes and inland trades. It offers comprehensive benefits and training through the Paul Hall Center.

Nautilus International is a trade union and professional organization representing maritime professionals in the UK, Netherlands and Switzerland. It specifically focuses on the needs of officers, cadets and other maritime professionals.

The AMOU represents deck officers, marine pilots, marine engineers, and maritime industry professionals across Australia. It focuses on improving working conditions and professional standards for maritime officers.

MEBA is the oldest maritime labor union in the United States, representing marine engineers, deck officers, and unlicensed seafarers. It specializes in representing the interests of marine engineers and other licensed officers.

NUMAST represents maritime officers and professionals in the UK merchant navy and shipping industry. It merged with the Dutch officers' union to form Nautilus International in 2009, but maintains some separate operations.

AMOSUP is the largest seafarers' union in the Philippines, representing both officers and ratings. It provides comprehensive welfare services, training, and representation for Filipino seafarers worldwide.

MM&P is a maritime labor union representing licensed deck officers and maritime professionals on U.S.-flag commercial vessels and government-operated ships. It focuses on professional development and job security.

NUSI represents Indian seafarers working on Indian and foreign flag vessels. It provides comprehensive welfare services and advocates for improved working conditions and rights for Indian maritime workers.

SMOU represents maritime officers working on Singapore-flagged and foreign vessels. It focuses on professional development, welfare benefits, and improving working conditions for maritime officers.

AIMPE is Australia's oldest maritime union, representing marine engineers across all sectors of the maritime industry. It provides specialized support for engineering professionals on vessels of all types.

The Marine Pilots Association represents maritime pilots who guide vessels safely into and out of ports. It focuses on maintaining high professional standards and advocating for safety in port operations.

IMEC represents maritime employers in collective bargaining with seafarers' unions. While not a union itself, it works closely with unions to establish industry standards and fair employment practices.

The Norwegian Maritime Officers' Association represents deck officers, engineers, and other maritime professionals working on Norwegian vessels. It focuses on maintaining high standards and fair compensation.

The Maritime Union of New Zealand represents seafarers, waterfront workers, and other maritime professionals throughout New Zealand. It was formed through the merger of the Waterfront Workers' Union and the Seafarers' Union.

ver.di Maritime is the maritime section of ver.di, one of Germany's largest trade unions. It represents seafarers, port workers, and other maritime professionals across Germany's maritime industry.

SEKO Seafarers is the maritime section of SEKO, representing Swedish seafarers and maritime workers. It focuses on maintaining fair working conditions and professional standards in the Swedish maritime industry.

The Maritime Union of Australia represents workers in the maritime industry, including seafarers, stevedores, port workers, and offshore oil and gas workers. It is now a division of the Construction, Forestry, Maritime, Mining and Energy Union (CFMMEU).

The Federation of Merchant Marine represents seafarers from Panama and other Latin American countries. It focuses on protecting the rights of seafarers working on Panama-flagged vessels, which make up a significant portion of the world's merchant fleet.

Unifor Maritime is the maritime section of Unifor, Canada's largest private sector union. It represents workers in various maritime sectors, including shipping, ports, and shipbuilding.