We went last Sunday and were the only people there. A lot of hotels include free passes to this. A cool thing about the waterpark is that the pool and hot tub are side by side and almost the same size. This place could be enjoyed both crowded and empty.
Many businesses are prepping to shut down for the season. Hopefully this one stays open for a little while longer. It's a bit expensive, but well worth it.
I took these from the balcony. The hotel is located on S Huron Ave (23). My brother-in-law paid about $58 per night. Pool (open till 10pm) and hot breakfast included.