To update : we found the basic snorkel stuff at a very nice mega Ace in Cole Bay. We intended to go to grand Marche but got sidetracked with our exploring and instead stocked up on the prosciutto we were seeking at a lovely store called Grape Wine just outside of Grand Case. Finally, Mahokid, a trip to Le Cottage is likely in the cards for us as well so perhaps I will get to say hello. Cheers, all, and thanks for the tips.