The trip is worth the money. We stopped at cuban coffee queen for some iced coffee and made our way to the boat (they do have breakfast available on the ferry). The fairy is large and comfortable. We took the guided tour of the fort when we arrived, had lunch, and then spent the rest of our time snorkeling and on the beach. The water is gorgeous and the snorkeling was decent. The boat is available to you all day if you need restrooms or a break from the sun. Its expensive but I think it is a great day trip option while in Key West. We were back before 5pm, so you won't miss any evening activities.