when we were there in Sept - the hours listed - did not always happen - there was only one person who worked this counter - if she didn't show up it would not open - and sometimes she had to close early.
If you get near the Turtle Shack make sure one day you are at OKW around lunch time - if she is there - she will be opened so ask her.
I think the published hours are 10:00 am to 6 Pm - but she closed at 3:00pm a couple of time when we were there. She was very nice - before she closed - she went around and say last called for drinks and explained that she was closing.