if you use salon or spa services that will cost you extra
some classess in the gym have a fee attached to them
if you buy any of the photos that the ships photographer takes
alcoholic drinks - buy your fancy frou-frou drinks when they are on special
expect to pay for a good bar drink about the same as you would back home at a good restaurant or nice tavern.
Soda is extra - if they have a soda card/sticker and your son or anyone else likes soda its a good deal - average price for a soda on a ship $1.75-$2.00
If you order from room service,you will not pay extra for your meal, but if you order a drink or a soda there will be a charge - tip the person who brings your room service meal a buck or two.
Some classess/seminars have fees