There are a few of those sailings.
You could use a TA or book on the website on your own.
Technically at this point passports are not required on a closed loop cruise (per my TA this could change -it was supposed to a few years ago), BUT if there is an emergency that leaves you in Nassau (or evacuated from CC or the ship to a non-US point; or if for some reason the ship has to disembark passengers elsewhere and you have to fly home) you would have to get an emergency passport there before you could fly back. Not what I would want to deal with in an emergency.