I was standing at Lee Street, Sydney right behind this suit at pedestrian crossing when this Hop-ON-Hop-Off bus passed. This service is operated by Big Bus in Sydney.
There are other operators too in different parts of Australia with similar service but this one is most popular. Sydney is big and beautiful city and traveling by open air bus is really fun.
I wish they brought this service under $2.5 for any transport including the buses, trains and ferries which would make this service even more enjoyable. A must have in your list while traveling in Australia.