Although modern ships have significantly reduced their environmental impacts relative to their size, cruises remain a major source of air, noise and marine pollution. 
However, while the capacity of the biggest new boats – which can accommodate up to 8,000 passengers, equivalent to the size of a small Mediterranean town – is a key factor behind the environmental impacts of the industry, smaller boats can also harm the marine environment.

More info
Final recommendations of the PHAROS4MPAs project regarding the cruise sector in the Mediterranean
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