Excursion to sandbar and island?

Has anyone done this excursion? Described on Celebrity website as a trip along the shore to a sandbar in the water where you can float around and then a stop at a little island. They have an adults only one and a more family oriented one in the afternoon.

Question: How do you board and unboard the boat? Stairs in the water? Ladder?

Sorry, my former post is for Labadee, Haiti

Check out this thread

http://boards.cruisecritic.com/showthread.php?t=2049812&highlight=malfini