Hong Kong (SAR) consists of three parts.
Hong Kong Island is located just off mainland China. It is right in the middle of the Pearl River Delta. Several hills run across the island roughly from the east to the west, the highest of which is the Victoria Peak. Along the coast is a fairly narrow strip of flat land, much of which was reclaimed from the sea over the years for habitation and roads.
North of Hong Kong Island, separated by the harbour, is the Kowloon peninsula, which is triangular in shape. Travelling across the harbour by ferry, which takes about 8 minutes, is a great way to understand this densely populated world. By the way, Kowloon means 9 ("kow") dragons ("loon"), because overlooking Kowloon are nine peaks stretching from the east to the west, like dragons. One of these peals is called the Lion Rock because the top looks like the head of a lion.
The rest of Hong Kong, consisting of the New Territories, takes up about 92% of the land. It includes the land between Kowloon and mainland China, and the neighbouring islands. A large part of the land between Kowloon and mainland China is flat and was once used mainly as farmland.
The largest of the islands is called Lantau Island; it is quite mountainous and much of it has not been developed or populated (which is a good thing). The international airport and Hong Kong Disney are located along its coast. Near the top of Lantau Island is a plateau, which has a large Buddist monastery; from the plateau one can climb up the peak (which takes about one hour) to watch sunrise.
Along the coast of the whole of Hong Kong are many beaches, bays, inlets and coves. Several beaches on the south side of Hong Kong Island are easy to reach and are popular with the residents for swimming and picnics, especially in the summer.
The not-so-easy to reach inlets were great as hiding places for pirates, and were so used by them more than a century ago. Of course, pirates in the region are no more, and these places are great for fishing and swimming if you are able to hire a boat to get to them.