A new UK report shows how maritime services have helped the local economy with jobs and the nation's gross domestic product
Research carried out by consultants Oxford Economics says the industry is worth £25bn ($35.7bn) per year and contributed almost 2% of gross domestic product.
It also shows that one in 50 workers are employed in the maritime sector.
The report was commissioned by OneVoice, the body representing UK shipping, ports and maritime businesses.
Nautilus' general secretary Brian Orrell said the figures demonstrated the continued significance of shipping-related industries and services to the UK.
He added: 'The sector depends on a steady flow of maritime skills and experience for its future, and the research underlines the urgent need for the government to act on the industry's proposals for safeguarding British seafarer employment and training."
Meanwhile Indonesia is defending its policy of cabotage, requiring all vessels operating in Indonesian territorial waters to bear the country's flag from 2010, Fairplay reports.
The move is expected to affect the coal and oil industries in particular.