All rooms have two twin beds that can be pushed together to form a queen or king for the 1st & 2nd Guest (except for Carnival 1A -Cabin with bunk beds category); Sleeping spots for Guest 3 & 4 might be a pullout sofa-bed or upper bunks that fold down or pull down from the wall or ceiling. Sometimes can also be a trundle bed or rollover bed.
All cruise lines provide Pack 'n Plays (or similar portable cribs) on request for babies, depending on availability. It must be requested at the time of booking.