Celebrity usually allow smoking on the starboard side both in the bar and when outside. They don't encourage you to smkoe in your stateroom but if you ask you should get an ashtray. There are no smoking in the dining rooms or the theatre. The ventialation on these ships is excellent and this takes care of the smoke problem whether in your stateroom or in a bar but NEVER smoke when lying in a bed and where possible use the balcony if you have one but discard your cigarette don't throw it off the ship as it could be blow back in and case a fire !!
All RCI ships will not allow smoking in the cabins from Jan 1st 2008. If you have a balcony then you can smoke on that - otherwise you will need to go to the designated areas.
Queen Victoria is the new baby of Cunard, launching on the 11/12/07. You may smoke in designated areas however caution to the wind..as fire is enemy number one! Bon Voyag.
As this question is about RCI Mariner of the Seas my original answer stands - NO smoking allowed in the staterooms. If you do then there is $250 'cleaning' charge applied to your bill.
You are allowed to smoke in certain areas of some of the decks but not allowed inside at all. We've just been on the Mariner of the Seas so if you've got any more questions just let me know,