When you tender in to the port(the ship does not pull right into port, a ferry takes you from the cruiseship to the port) there is a beach right there in the open. I have never seen nudity in that area.
CRUISING CROWN PRINCESS JULY2-11,2006
Crown Princess 8/10-8/19/07
Crown Princess 8/19-8/28/07
This is an old post, but hopefully the OP will come back for another answer. First, there are docks at St. Maarten. I have never had to tender there, maybe the other poster was confused with Cayman Islands??
Anyway, any of the beaches on the Dutch side are more modest. Mullet Bay Beach and Maho Beach are quite nice.
you get off the ship. then walk to the ferry which is 5 dollars to use all day long. it takes you to a dock which is at a beach. bars, the shops, everything is there. you can lay out right there, and enjoy the 1 dollar beers!