Since Hong Kong is at the mouth of the Pearl River in Southern China, the city's transportation has centered around the water. In the past, junks (a style of boat) and fisherman ferried passengers on short trips. Today, the numerous ferry lines connect Hong Kong to its outlying islands and even other parts of China such as the city of Macau or Guangzhou. And while not your typical transportation, my friends and I even took a short trip abroad a small boat known as a punt. It was quite an experience taking the small raft.
I also noticed that while cars are pretty popular in the rest of China, not a lot of people own their own car in Hong Kong. This is probably due to how packed the city is. Most of the land is actually mountainous and so millions of people are packed along the coast. A parking spot could, therefore, cost a fortune in Hong Kong.