premise: Good  cloth hangings of Creole scenes, seashell jewelry, straw mats and hats, particularly from Saint-Barth??lemy, local rum, and conch shells (beautiful specimens can be had for just a few francs apiece from curbside peddlers near the maritime terminal, but only when a cruise ship is about to depart).
hypothesis: When cruise ships are about to head out, it's a good time to buy cheap souvenirs from curbside peddlers.