I think that is going to vary from country to country and ATM to ATM. You'll have to wait and see when you get there. Most of the ATMs we saw have an "english" button so that you can read what you are agreeing to. If your card does not charge an exchange fee then you are in good shape but I would expect to pay a ATM fee at most machines.
If you have a "free" network you can use, go to their website and see if they have machines in the places you are going.. it may give you an idea of how likely it is you'll be able to find a ATm in your network there.
Carnival Cruise Lines:
Fantasy 90, Celebration 95, Victory 05, Conquest 05, Spirit 6/06, Freedom 6/08, Holiday 7/08, Victory 6/09, Valor 9/09, Dream 6/10, Splendor 8/10,Conquest 8/11,Magic 11/11,Triumph 4/12,Spirit 7/12,Freedom 11/12, Triumph 2/13 - The fire cruise
NCL Dream October 2006, RCCL Mariner OTS June 2007