Darling Harbour is a favourite spot for kids to get saturated in public. The various fountains and sculptures on the Harbour seemed to invite participants to leap and explore and inevitably get covered in water. This obviously did not escape the attention of the council that has constructed a vast adventure playground out the front of the Convention Centre.
Spiderwebs and dams beckon children and adults alike to imagine and play. The scale is huge. The metallic rope spiderwebs give the feeling of being a tiny insect. This is contrasted with a section of dams and canals that give one the feeling of being some omnipotent overlord, deciding the fate of dreamed cities.
It does not cost a cent to go there. The kids will more than likely enjoy this over other more expensive activities if you stop an d observe other children rapt in their enjoyment.
A few keen businessman understood the needs of the parents, and as such there is no shortage of food and coffee options within earshot of the play equipment. There are a few a little further away too if the kids are getting you wound-up.
I would not suggest driving as parking in the city is a nightmare. The best way to get there would be either monorail, tram or walking. The nearest train station would be central.