When I began to research travel by freight boat, I was hoping it would be a cheap alternative to air travel, but it turns out you can expect to pay US$80-140 per day and voyages are often five days or even longer.
However, I'm curious whether anybody knows if there are freight boats that go between islands in the Caribbean, for example from Dominica to Martinique. If so, how does one book a voyage on one of them? Do you have to go through a travel agent? Is it cheaper than flying?