See Antigua by Sea-We did a boat ride around the island on a beautiful yacht. Stopped at a very nice private beach and did some snorkeling. Enjoyed it very much. My only complaint is that they did not have enough of the size fins for everyone that needed them. One of us ended up having to use broken fins. Also, we did not have an issue with this, but the north side of the island is the Atlantic Ocean (rockier than Caribbean Sea)and we had a very seasick passenger so please beware if you do tend to get sick.
Here we just did the open air taxi ride around the island. It's a great way to see the island without doing a formal excursion. Taxi drivers definitely must get a cut of profits for bringing you to their tourist stops (rum distillery which was just a place to buy a bottle of their local rum, not actually a distillery that we could see) but that's somewhat to be expected. The island had many beautiful ocean views.
This was a bit expensive but something we really wanted to do. Overall we had a blast and also wish we had more time here (we were only in port from 12:30 pm to 6:30 pm and aqua adventure closes at 5pm). Fish tanks and aquariums were in need of some cleaning (especially shark tank you go through on water slide), but with that much to keep up, I can see why. Overall, the amount of attractions of the water park was less than I was expecting (around 4 or 5 slides and 2 adventure/lazy rivers total) but given we only had 4 or 5 hours, we got to do everything we wanted.