Here is a list of places for buying food, or for just walking around and enjoying the Caribbean street life. There are more supermarkets on the island, but in this list we just concentrate on our immediate surroundings.
Roseau has a busy and beautiful Farmers Market. It is open every day of the week, though Saturday is the busiest day. It is located close to the water where the Roseau River flows into the sea. You will find tons of locally grown vegetables and fruit, plus spices and other things needed for cooking. The market is definitely worth a visit.
At the sea side, opposite the Farmers Market, is the Fish Market. There is no particular best time to come. The fishermen will sell their fish when they come back from fishing, and this can be any time of the day.
There are a few small mom-and-pop stores up the hill in Trafalgar, selling all kinds of things including groceries and bread.
There is a large choice of supermarkets in Roseau, offering everything you need. Some of them have pharmacy sections.
The Fresh Market (with Pharmacy)