You would want to take water taxi or land taxi. I have only done land, you will find them all over, takes about 10 to 15 mins by cab from the port. Atlantis is the only thing really worth going out of your way for. It's very fun but pricey and I plan to skip it on my next cruise as getting there and back and enjoying it takes the whole day. I know your supposed to have a special pass you do the aquarium but I never saw anyone checking. My advice is if your not super big on waterparks(because the beach at Atlantis is really not worth it). Get off the boat, maybe do a little shopping and grab a bottle of wine to bring back or a six pack, and get back on the boat earlier to enjoy the pool while crowds are downjust curious, can you walk to Atlantis or is it a cab ride? and, can you just go to Atlantis and explore if your not staying there or have water park tickets?