Ahoy there, Lauren! Welcome!
Disney Cruise Line lays it out fairly clearly when it comes to required
travel documents, and it's been fantastic during these times of uncertainty to see that Disney has constantly monitored changing requirements. It's been a huge help to me as I've planned my own cruises over these past couple of years.
For what is known as a closed-loop cruise, which is one that starts at a port in the United States and ends at a port in the United States, citizens of the United States do not need to present a passport. You'll have the option of either providing a passport or a state-issued birth certificate and a government-issued photo ID. Children under the age of 15 do not need to present a photo ID, but they will need a birth certificate.
I do encourage you to consider applying for passports for your family. Should a situation arise that requires you to return home from one of the Caribbean ports, the process can be very complicated without a US passport. I know of people who have had a lengthy, red-tape-filled trip home from the Caribbean because they haven't had a passport with them.
You're hitting some of my absolute favorite places, Lauren! I do believe I could live on
Castaway Cay if they'd let me, spending my days snorkeling and enjoying Cookie's BBQ. There are some outstanding
Port Adventures on the island, so book as soon as you can. My family loves the
Banana Boat Ride.
I hope you have an amazing voyage, Lauren!
Anna