This is a great short and waterside walk in the Sydney CBD, perfect for the evening after work during summer! You can watch the sunset. From the southern end of Barangaroo Reserve (where the casino is being constructed), you can walk along the water's edge all the way up to Walsh Bay. The sandstone steps leading into the water mean that you have an uninterrupted view and can even have a dip if you want. The steps also make for great seats to just relax and enjoy the view.
If you want to get up higher, you can take the stairs up to the flat grassy plain at the top, called Stargazer's Lawn.
The Barangaroo Reserve is a great space to go for a walk, take photos and just enjoy the view.