If you’re visiting Sydney this is the best advice someone can give you:
– Get the public ferry from Circular Quay to Manly!
Sit on the back of the ferry on the way to Manly and on the front on the way back (you can make the way back at night to get a different picture of the city).
For some strange reason this route isn’t usually considered a tourist atraction in Sydney and the typical tourist tours will instead take you to more expensive cruises to show the Harbour Bridge and the Opera House. However if you like to keep to your exploration and pace, going to Manly is a superior experience for a completely affordable price. If you prefer you can even pay with the Opal Card the same way as you do in the city buses.
I’ve made a video of part of the trip but if I were you I would only see it after I’ve made the trip myself:
Also worth trying in Sydney: Take a tour in the Opera House ; Go to Koala Park ; Walk around the Opera House botanical gardens ; Cross the Harbour Bridge.
Song on the video: Blitzwood – Into my Dreams