Both in St Thomas and San Juan we disembarked from deck zero. The whole process is short and easy.
It is possible to take some fruit or a sandwich ashore especially if one does not want to have lunch on board.
While leaving the ship the security just scan the SAIL AND SIGN card.

In order to embark, you must have your ID with a photo and the SAIL AND SIGN card. Your bag is x-rayed and you go through a metal detector gate. Still the embarkation is fast.