Nautilus International is an international trade union and professional association representing seafarers and allied workers, which is based in the United Kingdom, the Netherlands and Switzerland.

The union's head office is in London, UK; its General Secretary is Mark Dickinson.

[2] This includes "shipmasters, officers, cadets, ratings, yacht crew, VTS officers, harbourmasters, river boatmen, nautical college lecturers, maritime lawyers and even ship-based medical personnel".

[3] On 2 October 2006, the British National Union of Marine, Aviation and Shipping Transport Officers and the Dutch Federation of Maritime Workers formed the Nautilus Federation.

[4] In 2008, members of Nautilus UK and Nautilus NL voted overwhelmingly in favour of proposals to create a new single trans-boundary union for maritime professionals.