Every visitor to Sydney needs to have their picture taken in front of the Sydney Opera House. The dramatic architecture of its multi-shelled roof makes it the landmark structure of Australia. It sits in a picturesque spot on Sydney Harbor so that it can be seen from just about anywhere on the water. You can see a show there but it will be expensive and it does not look nearly as spectacular inside. For a panoramic view of Sydney, head up the Sydney Tower. The ticket includes "OzTrek." It is a 3-D hologram movie of all the sites of Australia.
Sydney is best seen from the water. The Sydney Harbour Cruise takes you under the Sydney Harbour Bridge, by the Sydney Opera House and along the Sydney skyline. This is a leisurely cruise with many photo opportunities. You can get an abridged version of the Sydney Harbour Cruise by riding the ferry from Circular Quay to Manly. It is not meant to be a sightseeing tour but it goes past all the big sights. You can also zip around Sydney Harbour in a high speed Jetcat if you have a need for speed.
The other famous landmark in Sydney is the Sydney Harbour Bridge. You can climb to the top along the curved edge. It is a memorable experience that provides a spectacular view. Just be sure that you are in decent condition and don't have a fear of heights. The climb is moderately stressful but well worth the effort.
Sydney is home to some beautiful beaches. Bondi Beach is the most popular. It attracts a mix of tourists and Australians. It is fun to go there to soak up the sun and the atmosphere. The waves are quite nice at Bondi making it an ideal surfing beach. Coogee Beach is also one of the best in Sydney. It offers one of the most spectacular views of the sea in Australia. You can walk there from Bondi Beach. Manly Beach has a perfect crescent shape and is lined with restaurants and bars. It has much more of a resort feel than Bondi or Coogee. Get there on the ferry from Circular Quay.
Sydney Aquarium is one of the best anywhere. There is more sea life there than any other aquarium in the world. It has several submerged observation tanks where people are in a box inside a giant pool of water. Sharks, sea lions and giant manta rays swim around you. It is like you are in the fish tank in their world. Try to visit during feeding time. Manly Oceanworld is smaller but allows you to swim with the sharks.