

I’d be interested into some data on this topic.
My undersranding is plane is one of the most polluting mode of transportation, all things being equal. It probably vary a lot depending on the specific ship/plane, route, …
Data from the UK’s Department for Energy Securityand Net Zero (2022) shows the carbon footprint is 8x higher for short/long-haul fight than for ferry. (CO2eq per passenger-km). Carbon footprint is strongly coupled with fuel consumption. It’s not quite the same, but I’d expect the ratio to be roughly the same.
Thanks. This explain why cruise ships are much more wasteful than ferries:
This is why it’s important to compare transportation mode all things being equal. Keep in mind there’s lot of people flying coach, very few planes with individual cabins and restaurants. Cruise ships are designed for entertainment and luxury. Ferries are designed for transportation.