I go solo and love the waterparks.
I don't bring anything with me other than my card key/ticket and a swim chamois to dry off. I keep them in one of the cargo pocket of my swim trunks (I'm a girl, but my dad died of melanoma and genetically at risk, so I wear long swim trunks, a tank top, and a floppy hat when I'm at the water parks to keep as much sun off of me as I can). I only go for two or three hours, so I don't need food. When I need something to drink, I get a cup of free ice water at one of the restaurants.
The last time I was there was in 2008, so things might be different, but here are some things I remember:
There were only two rides that gave me problems - a family raft ride at BB, but a family of 3 let me ride with them. It was a little weird. I don't have a problem riding with other people at the theme parks, so I'm not really sure why... And the Crush 'n' Gusher at Typhoon Lagoon only had one slide that singles could go down. I lugged my raft up and waited in line, only to be told that I could only use a specific slide. That was pretty annoying. They let me on it right away, but I couldn't use either of the other slides unless I found a stranger to cuddle up with. One good thing, though, is that BB had a single rider line for the chair lift, so it took only a few seconds to get on a chair.