From Cir­cu­lar Quay you have a great amount of options for fer­ry rides the kids will love. The loop from Cir­cu­lar Quay to Dar­ling Har­bour will give great views and last an hour. Fer­ries to Man­ly, Wat­sons Bay, Taron­ga Zoo and Par­ra­mat­ta all have much to see. Alter­na­tive­ly the King Street Wharf in Dar­ling Har­bour has some good trips as well.