Nautilus International is an independent trade union and professional organisation representing maritime professionals in the UK, the Netherlands and Switzerland. The organisation describes itself as a global and influential voice for seafarers and other maritime professionals, committed to delivering high-quality, cost-effective services to members alongside welfare support for those in need.

The organisation works to support members on employment-related matters, professional issues and wider sector challenges, while also campaigning with governments, international agencies and the maritime community to improve working lives across the industry. Nautilus International highlights its role in creating change on issues affecting maritime professionals, as well as providing specialist support, member resources, events and career-related services.

Nautilus International positions itself as a specialist membership body for the maritime sector, combining representation, advocacy and practical support with a strong professional identity. Its website also highlights a wider offer that includes legal and workplace support, member benefits, training and industry insight, helping serve a diverse maritime membership across multiple countries.