Can I add Waterparks Later to my Park Hopper?

[CVW]

I'm buying a six day park hopper for our upcoming trip. We haven't yet decided if we want to visit the waterparks. Can we upgrade to the waterpark later for the same price?

 

[may1787]

I am curious about this as well. My days look pretty full, but I may decide to skip a multiple Magic Kingdom day and visit a waterpark instead.

 

[Robo]

I'm buying a six day park hopper for our upcoming trip. We haven't yet decided if we want to visit the waterparks. Can we upgrade to the waterpark later for the same price?

Yes.
Even on the way into a water park, if you like.