Hi Erin,
The
Magic Your Way Package base package includes a resort stay and parks tickets that provide you with admission to one of the four Disney theme parks per day. The four theme parks are the Magic Kingdom, Epcot, Disney's Hollywood Studios, and Disney's Animal Kingdom.
You can choose to add the Water Park Fun and More option which will allow you a certain number of visits based on the length of your ticket to either of the two water parks, DisneyQuest, or the ESPN Wild World of Sports Complex. You can read more about the add-on at the above link.
If you think you will only be going to a water park one day out of a multi day trip, you may be better off buying a one day water park ticket.
The
Tickets and Passes website has a lot of information about the rates and packages available.
Enjoy your trip - Michelle