Didn't they start this last year, or was it the year before? I know a lot of water parks are doing similar things now, so I might be confusing it with another park.
Just another way the industry is trying to diversify itself and get a leg up on the hoards of community water parks. I really don't see the attraction in this, but it must be working. It's tough for waterparks to have any festivals or events that aren't based around playing something while everyone is in the wave pool.