This is a great off-leash dog park. My favorite part actually isn't the dog park though it's the walk down to it when you enter from just north of Eglington. There's a long walk down a hill from the back yard of sunnybrook. It's all paved and on either side you've got great mature trees. On the north side it's a drop down so you don't want to have your dog off-leash unless they're trust worthy.
Another great but almost hidden secret at this park is that there's a swimming spot outside of the off-leash section. If you go out the south-west exit and stick to the right of the stream then you'll find a nice spot where dogs can wade into the water and swim. It does go deep though and there can be some current so be weary of balls floating away if they're not instinctive retrievers.