Are there plenty of markets for basic foods?
Yes, I encourage you to take snacks you love and that travel well- you may not be able to find all of them there. The Greenhouse on Front Street is a great food store. I also go to Marinass near Sunset . I buy cokes and beer at the Belican distributorship. I do not usually drink beer, but the Belize beer is very tasty! There is also a good wine store called Wine Divine. There is a fish market (hard to find-ask around) and small fruit and vegetable stands in many places. There is also the large Super Market that is more expensive, but carries a lot of familiar foods/brands.
