Cruise ships are the worst invention since world war 2. A sort of a swimming city with thousands of people driven by heavy oil (not even diesel)! Not only driven in terms of movement, also driven in terms of generation of electricity by the worst source of fossil fuels.
This is bad on the open sea but it is even worse in the ports of the cities where these ships anchor overnight, blowing all their emissions into these cities. We know this is an issue of infrastructure in the ports but if there is no infrastructure for a reasonable supply of energy then do not do the business. And people, do not use any cruise ship that is driven with heavy oil. This is not fun; this is a crime. The cities that suffer from the noise and emissions of such ships, just should not allow them to anchor.