We took a pontoon boat from the shore out to the semi-sub. A semi-sub looks like a regular boat above water, but it has a sort of basement with windows all around where you look out and watch the marine life. The staff on the semi sub were very helpful in getting us aboard safely. I think this was the highlight of the trip for many of us our group. Then we took a very informative taxi tour around the island. Was disappointed in how run down it is, but at the port Carnival had a wonderful shopping area, complete with huge swimming pool and Margaritaville. I loved the pool. Could have stayed there all day.
We took a tender boat to the shore. The water was beautiful, the weather hot (but I like it that way). I am not a beach person, so I would have preferred that there be a swimming pool there. Maybe someday. I know that Carnival has spent millions on building up the port and is continuing to make improvements all the time.
My husband and daughter took the bicycle tour and loved it. They got to see a lot of the island in reasonable amount of time and the terrain was easy and flat which made the tour enjoyable.