They give you bands that they check (sometimes) and sometimes they don't. You can actually see quite a lot of it without going past the check points (entrance tunnels).
As you enter the casino....there is a staircase that takes you down a level where there is a HUGE tank. Then if you walk through the gardens (again these are unattended) you can see lots of the place for free.
As stated earlier, even the bands do not give you access to the pools, slide or beach.
Personally, I would walk down the stairs and see the tanks and if no one is at the tunnel entrance...just walk on in. As you walk through, if you come across someone official looking...just cross your arms so that your left arm is covered. Again, if you get "caught" just play dumb and ask where you can buy a ticket. They will tell you. It isn't like they follow you to the desk to make sure you buy one.
It takes about an hour to leisurely walk through the whole thing that goes through the gardens...and was worth the $25 each to us last time we went. ($19 for children)
Definately an excursion you can do on your own....no question.