I just recently got back from a week in Belize, had a wonderful time, beautiful country and people and definitely want to go back again. One thing I did notice was the amount of trash (mostly plastic) washing up on shore at the beaches at various places along the coast.
My friends and I got to talking to some of the bartenders/owners at a couple of the local bars/restaurants in Ambergris Caye, and they told us that a lot of the garbage that washes ashore comes from the cruise ships that dump non compostable (yet possibly recyclable) trash out in the ocean miles from shore and it washes up all along the coastline, ruining once pristine beaches. I noticed things like plastic diaper boxes, plastic utensils, cups, many of these things with English writing/advertising on them. Some of them said they had even witnessed the actual dumping from the ships at night or early in the morning. I have never been on (nor have ever had the desire to go on - now even more so) a cruise so may be a bit naive to how they operate but had no idea that this kind of thing happened and quite honestly am disgusted /angered by it. It looks like some countries have laws which prohibit cruise ship dumping off their coastlines but a lot of areas in the Caribbean do not as they do not have the facilities to accept cruise ship refuse. It really blows my mind that the cruise companies can get away with this. It's a shame that some countries who go out of their way to remain eco-friendly have to deal with this. Although I am sure not all of the trash is from ships and could be floating from neighboring areas, I never have really been interested in doing the whole cruise thing and this really solidifies my opinions on them.