Jamberoo has been around for years and that's because it's a fun family outing. It's a 1 hour drive from Sydney but well worth it, with plenty of waterslides and other activities, such as mini golf and bob sleds, to keep kids busy all day. The Rapid River ride and Billabong Beach are perfect for toddlers and preschoolers.
Formerly Wet n Wild Sydney, Raging Waters has all the same slides and attractions as before, the name change is just due to new ownership. Open in spring, summer and part of autumn, this park is ideal for babies right through to teenagers. It has the Beach with a wave pool, the Nickelodeon water splash play area, Dinosaur Lagoon where you can float through a whirlpool, and 42 different waterslides, including the new Whirlwind that opened in summer 2020.
Sydney Olympic Park has several places where kids can have fun with water. First the splash park at Blaxland Riverside Park, which also has a cafe, and the fountains in front of the Triellage Tower Tower in Bicentennial Park, plus the Cathy Freeman Park which has the cauldron water feature. One of the best pools for kids is there too, the Olympic Park Aquatic Centre which has a water playground with a giant tipping bucket, whirlpool, inflatables and water slide.