Only way to use the pool, slides and beach is to be staying there or at the Comfort Suites. You can pay $25 to tour the indoor aquarium (The Dig) but not sure if it will get you to the outside ones. When we stayed there, they posted staff right outside the doors to the pool areas checking for wristbands (only for guests and they changed every few days). I think theres no charge to use the casino. Its an awesome place to spend a few days, but the staff wasnt very friendly or helpful when we were there. And it aint cheap either!
you can use the beach if you get a room at the Comfort Suites, you cannont use the waterslides etc unless you have a room at Atlantis, very expensive.
You can tour the aquarium for a fee.-Amazing.
You can walk around the casino and gamble without being a guest of the hotel. The casino itself is gorgeous. They have a great sportsbar with really good sandwiches.
We were on the beach a little way down from the Atlantis and walked over to their beach area. We walked right up to the pool area and swam in their pool with no problem. We also walked through the outdoor aquarium and toured the inside of the resort...fabulous place. We had no problem just walking right up to the pool and getting in. It was wonderful.