Getting around in Hong Kong, including crossing the harbour from Hong Kong Island to Kowloon, or to some of the outlying islands, is easy because it is served by many forms of public transportation. Taxis are available everywhere.
MTR, the subway system, is the main transportation network as it is much faster than surface transport and reaches most of the populated areas. Fare is charged based on distance travelled and can be paid by a single-trip ticket or by the Octopus card (which is a debit card). MTR also operates the Airport Express which connects the airport to the Central District on Hong Kong Island, with several stops in between.
Buses operate many routes which cover all of Hong Kong, including routes run through the tunnels which link Hong Kong Island to Kowloon. The fare is also based on distance travelled. Minibuses carry 16 passengers; some of them run routes which are similar to those of regular buses. They may be faster but cost more because they do not stop when full unless passengers have to get off.
On the north side of Hong Kong Island, which is where most of the residential and commercial districts are located, is a double-deck tram service which runs along the coastal road. It has been around for over 100 years. The fare is a flat HK$2 (lower for senior citizens and children under), and is probably the cheapest mode of transport if you go between the east and west of the island, and at the same time you can enjoy the views of the city from the top deck as the tram moves along.
To cross the harbour between Hong Kong and Kowloon, you can take the Star Ferry from Central to Tsim Sha Tsui, or from Wan Chai to Hung Hum. From the ferries, you can get a fantastic view of the city on both sides of the harbour. There are other ferry services which link Hong Kong Island to several larger islands including Lantau Island, Lamma Island and Peng Chau.
To reach the Victoria Peak, one should take the Peak Tram at least once. It brings you from the terminal up Central District to the Peak in less than 10 minutes as the tram climbs the hill at what appears to be 30 or more angles. So, if you are a standing passenger, you will have a really slanted view of the harbour and the city outside.