You can take the water taxi or a regular taxi over to Atlantis on Paradise Island. There are also ship excursions that give you a tour and you can see the dig/aquarium, its a wonderful way to spend a few hours.
tour the "Dig" this is the aquarium at Atlantis Resort. It is amazing. Just grab a taxi at the pier - either water or land, head over to Atlantis. Enter thru the gorgeous casino, there are kiosks in the casino where you can buy your tickets to the "Dig"