[belorn]

> It's just a less efficient means of transportation.

Boats could be a very efficient way of travel. Luxury cruise ships are inefficient because they general carries things like swimming pools, golf courses, major shopping malls and restaurants. The proportion of space and weight that is used for transportation is tiny compared to something like a train, buss or aircraft (or even a car).

Ferries in contrast has very low carbon footprint of travel per kilometer, as can be read in this graph: (https://ourworldindata.org/grapher/carbon-footprint-travel-m...).

Since container ships has a very high ratio of transported goods vs total weight of the ship, and those tend to have one of the lowest carbon footprint per ton/mile. It is one of many reason why things like ore is generally always preferred to be shipped by water.