All cruise lines give insstructions to carry a government issued ID and your cruise ship pass. I have been asked for the ID at many ports. Take both and don't augury about it.
Cruising on Carnival Magic, Sept 10, 2016 From Port Canaveral FL
. 7 days-Cruising on Carnival Magic Dec 3,2016--7 days from Port Caniveral--Cruising on Carnival Vista, 8 days, Jan 27, 2018 From Miami, FL