The Star Ferry has been crossing Victoria Harbour since 1888, and the seven-minute ride between Tsim Sha Tsui and Central is still the best-value experience in Hong Kong. The fare is a few Hong Kong dollars, and the view of the skyline — the skyscrapers of Central piled up behind one another, with the Peak in the background — is as good as anything in the world. Take the lower deck for the full old-school experience.
Ferries run from roughly 6:30am to 11:30pm. Most people take the MTR under the harbour; the Star Ferry is better. There's a second route connecting Tsim Sha Tsui to Wan Chai.