There's a dive shop in Le Marin. I'm not sure the name but I guess they do rentals, or the charter
company can put you onto a rental co. North or south, both directions are great for a few weeks. I'd lean toward north though. Dominica
is great for diving
and hiking, as is pigeon island off Guadeloupe
. Then up to Antigua and Barbuda
. The saints along the way and you could drop by Montserrat if time permits.