Most cruise ship do not have poker yet. The Princess line is starting to add low limit holdem, also Carnival. There are special poker cruises, look it up at cardplayer site.
On the Princess line, the Grand Princess was the first one to add poker room. I was on it just before they added the poker room, the cruise could have been for free if poker was on board then.
The newsletter I receive from Princess said they would be adding holdem to the other ships.
My favorite line by the way. Been on a few others and this one beats the others by a country mile. Great food & service.