This is an excerpt of a reader’s comment about cruising, a comment we stumbled across on the Internet:
“Cruisers are not aware of the acute environmental damage that they are doing to water and air sheds. Cruise ships are small mobile cities that dump their sewage into oceans and spew toxic emissions into the air.”
We are not apologists for cruise companies. What we are — or try to be — are custodians of the truth. The comment above is not true.
There was undoubtedly a time when cruise ships pumped sewage into the sea. All the cruise ships we have been on the last few years have environmental processes for dealing 
with sewage. By the time it becomes one with seawater, it has been reduced to “gray water.”
Now we haven’t actually witnessed the path the sewage takes — if somebody’s got to do it, somebody is not going to be us — but we have seen the equipment used to treat sewage. It’s an environmental responsibility the cruise industry has had to take seriously, and going on a tour of a cruise ship will give you some idea how seriously.
As for the spewing of toxic emissions, it would be incorrect to say there are none. What would be correct is to say that there are fewer toxic emissions all the time. Many ships are now powered electrically while in ports, enabling them to be moored without having to keep engines running for on-board power, and thus reduce emissions from the funnels.
It would also be correct to say that when anybody drives to the beach this summer, even the author of that comment, there are likely to be toxic emissions coming from the vehicle. In many of the things we do, we can’t avoid leaving a carbon footprint. The responsible thing to do is make the footprint as small as possible.
Also, not to believe everything that’s posted on the web.