Cruise ship pollution

When a cruise ship or passenger ship is in the middle of the sea, it creates a number of wastes that are harmful to the marine environment. From the operation of the ship alone, large amount of smoke is released into the air. The smoke pollutes the atmosphere with CO2, CO and other toxic gases.
A cruise ship with a capacity of more than 5000 passengers can be considered as a small floating village or town. The cruise ship produces huge quantity of solid and liquid wastes that have to be properly treated to minimize negative impacts which they bring to the marine and land environment. For example, the gray water. Even though gray water consists mostly of organic material, it should not be released into the shallow waters where there are coral reef because this fragile ecosystem will die if the water is saturated with nutrients. So, the graywater has to be filtered to separate solid wastes from it before it can be released into the sea.
Special waste processing devices inside a cruise ship are used to reduce the volume of plastic and metal wastes so that they will not consume a lot of spaces inside the ship's compartment. When the cruise ship arrives at one of her ports of call, the wastes can be transferred to land for further processing. 

The above Youtube Video shows how MSC Fantasia cruise ship promotes herself as a marine vessel that respects marine habitat. To minimize air pollution, the ship uses low-sulphur fuel. To conserve energy, the cruise ship uses energy efficient light bulbs in all of her passenger cabins and public lounges. Energy efficient air conditioning system significantly reduces fuel consumption of this vessel. Improvements in ship design towards a more environmentally friendly ship is a positive step in maintaining the growth of marine tourism industry without harming the precious marine environment.