If you're
provisioning in a U.S. port, especially if you don't have a car, look into the many
food supplies offered by Amazon.
Shipping is free on most orders over $25 and stuff goes right to the marina. I find items and brands there that are not available in local stores and buy in case lots for the free
shipping. Look for the words "eligible for free shipping" in the listing because items shipped directly from their suppliers may not ship free.) If you have special needs (sugar free, organic, non GMT, gluten-free, etc.) this is the most hassle-free place to find them. Amazon doesn't have the biggest and best selection of long-life and survival foods but it's an ideal source for many staples as well as specialties.