The beaches are beautiful, please remember the only public areas at Atlantis are the casino and surroundings, you cannot even enter the lobby unless you are a hotel guest or buy a package from them.
Only go down for the photo op next to the "welcome sign". The ship stays on port for 6 hours, nothing interesting to do nearby, unless you take an excursion. Remember the water is cold in the winter, don't book "Swim with the dolphins" or "Scuba Diving" during this time of the year.
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