Welcome aboard, Cynthia -
You'll be glad to hear that there's lots of activities available onboard a Disney Cruise for all members of the family... no matter the age! You'll have a choice to do as many or as little - your pick.
Once your son turns 18 years old, he is able to visit any of the adult exclusive spaces onboard. He will not be served any alcohol of course, since he needs to be 21 years old for that. There is even
Club*18-21 meetings on your voyage and that allows him to meet other 'big kids' his age between 18-21 years old. To be sure you don't miss it, make sure you've got the most current version of the Personal Navigator. If you look in the schedules page, the Adults area will highlight that day's activities and venues.
You'll be enjoying
Disney quite differently on a Disney Cruise, Cynthia! Have a great time planning your upcoming family adventure.
Have a great day,
~ Dolly