During certain port stops, your cruise ship will be topped up with fuel and smoking won’t be permitted on any of the exterior open deck areas. If you’re unfamiliar with the term “bunkering”, it’s the ship’s refueling process. Celebrity Cruises, Azamara, and Regent Seven Seas, among others, don’t allow smoking at any time in the casino. Today there are many cruise lines that have completely non-smoking casinos. Odds are it’s the casino’s non-smoking time.
If all the ashtrays have suddenly disappeared from what was previously a smoking section, just ask a crew member.
Some cruise lines have specific times where the casino is entirely non-smoking.