This ship used to have a chimney, but why not now?

Now most big ships also have chimneys, but it is not obvious.

In the past, there were tall chimneys on ships. Because the early ships used coal as fuel and were equipped with steam engines, just like the old coal-burning locomotives, thick chimneys were needed.

Nowadays, most ships use diesel engines as power, just like locomotives with internal combustion engines, they also have chimneys, but with less exhaust emissions, there is no need for so many chimneys.

See the smoke from the warship in the picture below? There is a chimney.

Chimneys on warships