The cruise sector, or more specifically cruise tourism due to the volume of trips and ships in the oceans, is becoming aware of its impact in terms of pollution, and for this is adapting regulations and investing in changing the type of fuel towards less polluting alternatives such as LNG, liquefied natural gas, which reduces nitrogen oxide emissions by 90% and reduces CO24 emissions by approximately 2%.
An example of this control by the institutions, and the companies themselves that do not want to end the goose that lays the golden eggs, is that fuel that exceeds 0,1 percent sulfur cannot be used in the Baltic, or that in the Venice lagoon, an agreement has been signed to use fuel with sulfur content similar to that which is mandatory in northern Europe.
The newest initiative for passenger cruises appears to be developing in Japan, with the Ecoship project developed by the NGO Peace Boat to reduce emissions by 40% compared to boats of similar dimensions. This non-profit organization was proposed in 2008 to obtain the Nobel Peace Prize, and has spent years traveling the world with different social purposes.
However A more immediate way to take care of the seas and the environment, reducing pollution levels, is to go on a sailing cruise. In this sense, the Sailsquare platform, which is a kind of Uber of the sea that connects customers and captains from sailing ships, has published a report in which it states that traveling between the Balearic Islands and Sardinia by sailing saves between up to 235 kg of CO2, which is more or less the consumption of a household of 4 people during a week.
If you want information about the policy that some shipping companies are carrying out to reduce the level of CO2 emission you can consult this article.