Pleasure Island.

A sorority full of hot-to-trot young sirens wins an all-expense paid trip to an island paradise. The four feisty femmes jump at the chance to spend a weekend away from all their problems, but their prim and proper housemother insists on coming along. Of course, once they get to the island, it's every girl for herself as they all set off in pursuit of vivacious vacation encounters. One by one, each of the girls wanders into Room 13 in their hotel, a mysterious realm in which all their sexual fantasies come true.