It's called Fireman's Park at White Sulphur Springs, which sounds really fancy (at least to me) but in reality, it's in the middle of absolutely nowhere. Unless you happen to live right there and then you
will probably be insulted by that statement. But you shouldn't be. The more time I spend in upstate NY this summer, the more I realize that I could totally become a local and would really be able to walk away from city life without a backward glance - except for that whole husband's job back in the city thing.
Anyway, I digress. If you should find yourself in the vicinity of Monticello, NY looking for something really fun (free) to do with kids (probably 8 and younger), then you should check out this park.
I could see this as being an awesome place to have an outdoor birthday party.
I could also see this park as being very crowded on the weekends.
So try to visit during the week. And bring snacks. Because, like in much of upstate NY, there is not a 7-Eleven to be found anywhere.