Some staterooms on a cruise ship can be warm, based on complaints I’ve seen in various cruise forums and Facebook groups.
Fortunately, I’ve never had a warm cruise cabin, and I like to keep it cool, but I do take a precaution each time I cruise.
One of the items I pack each time I cruise is a fan to use in my stateroom. I got a fan that clips to a shelf since space is limited. Also, I like to be able to plug it in so I don’t burn through lots of batteries.
In addition to circulating the air in your cabin, it also provides some white noise in case you are in a high traffic corridor on your cruise.
You can get one for around $20 and I’d suggest a compact model since you need to take it back off the ship with you.
Some folks have said they put a hat or towel on the thermostat to keep the air running, but I haven’t done that myself.