Hurricane harbor is not included by default. Unless you got the pass and processed it within a promotional period. 'Free upgrade to gold plus' is how i got free parking and free hurricane harbor.
You need to have the one that includes Hurricane Harbor.
Personally I've never been to Hurricane Harbor. However, I heard that you can. It is part of the park. Call the Park just to be sure.
I believe the membership passes included hurricane harbor. Some of the season passes may have get in free passes to HH. You should be able to review online
I bought the normal pass without flash pass since I went on a Monday and there was not much time in lines, but if you are going to go on the weekend it would be better to buy it but it is a bit expensive, and I did not go to hurricane harbor, only in the sixflags rides
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