Waterfalls in Oklahoma? You betcha! We have been several times, the last time was in the winter with my sister and her husband just to drink in the natural beauty (and skip the summer crowds).
This place is gorgeous and has great hiking trails, places to simply "wallow" in the water and fun falls you can swim or float under. Wonderful fun for a summer's day or a fall or mild winter's hiking. Nice little snack/gift shop and, although we have never stayed, there are some cabins on the property and nearby motels and it is close to more hotel options in Davis, Oklahoma.
The only problems are that they don't allow pets, the crowding and, for couples, the lots and lots and lots of seemingly unsupervised children. They try to keep the park clean and I've seen "housekeeping" entering the public bathrooms, but I'm sure it is difficult to keep up with the leavings of so very many people. My best suggestion would be to arrive and leave early, stake out a spot near the water (in the shade of the trees), and leave before the rest of the masses head for the exit!
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