Your best bet is to check with your travel agent as not all info is up to date but click here to view see the six-month validity rule anyway.
No, it is not a requirement if it is a closed loop cruise. Meaning you depart and arrive at an American Port.
HOWEVER. It is highly recommended that you have one, and I will tell you why. Say a family member gets sick or passes away while you are on your cruise. You CANNOT get home without a passport meaning you will be stuck until you come back to your US Port. If anything happens to you and you become injured and need to come home…you need to have a passport to leave whatever country you are in at the time. So while it is not required, it is definitely recommended.
When traveling out of the country it is recommended that you enroll your trip so you get travel alerts and warnings as well as enrolling your trip with the nearest U.S. Embassy or Consulate to know where you are if assistance is needed.
Click here FAA flight delay infofor a step by step guide.
You can always check the CDC website for updated information and what is recommended for vaccines. Click here to be redirected there.