We were in Dominica in January 2001 and went on a shore excursion arranged by Carnival. This was the only island that we stopped at, out of 5 ports of call, that they warned us not to venture out on our own. The cruise director flat out said that if you are getting off the ship you really should do one of our excursions due to safety concernces. Two weeks before we were on our cruise some people on that ship did their own excursion, from one of the millions of people that will be standing at the end of the dock trying to pimp you, and was seriously injured went the car went off a cliff. For other ports he had been real honest and told us which tours were rip-offs, ect. So we had no reason not to believe him.
The island is very poor, much poorer then any other island we stopped at. Everyone we talked to that went shopping at the area right off the dock was ripped off. Things from not giving correct change by trying to distract you to money being outright taken.
We went on the Pools and Falls excursion and it was truely beautiful. You do spend LOTS of time in the tour van because the two main attractions (trafalgar falls and the emerald pool) are on different ends of the island. The other excursion that was well rated was the champagne springs snorkeling tour. If we ever go back to the island on another cruise we are going to try that.