Hi Stephanie,
You're sure to have a blast at Disney's Water Parks! Currently,
Disney's Blizzard Beach Water Park is scheduled to be open during your visit. Additionally, depending on which dates in March you are visiting, you may be able to enjoy
Disney's Typhoon Lagoon Water Park as well. It is tentatively scheduled for annual refurbishment from January through mid-March, so you will want to check with Guest Services at your resort when you arrive to verify the scheduled Water Park operating hours. That all being said, I do not believe that you will have an issue with crowds in March. During the blistering heat of July or August, you might find that the crowd levels at the Water Parks are oppressive. However, in March, it is often only those of us from the north who would entertain the thought of swimming. In theory, you should be able to thoroughly enjoy light crowds and lots of laughs.
Thank you for visiting the Disney Parks Moms Panel and please let us know if we can assist you further.
Wishing you magical memories,
Kaylene