As has been posted in earlier pages, they won't just sit in port, not only to avoid paying port fees for each day they're tied up, but they have to sail underway in order for the water treatment system to make fresh water for consumption on board. Also since they're not able "hookup" to shore side power, they need to run the generators continuously so the port doesn't want the emissions from them settling all over the harbor area. So they'll go out and sail around and most likely anchor off shore for a few days or so then return to port for supplies, food and occasionally fuel. The Dream, Fantasy, and Magic are rotating between Port Canaveral and
Castaway Cay, with one ship anchored just outside PC. Then every few days they rotate, one will go to CC the Anchored ship proceeds into PC and the ship coming from CC anchors off PC and repeat. Even though the Magic is usually based out of Miami until she heads over to Europe they moved her up to the rotation out of PC due to lack of space in Miami, they have 7 to 8 ships docked there on a daily basis already.