Hong Kong consists of Hong Kong Island, Kowloon, and the New Territories. The Kowloon Peninsula is attached to the New Territories in the north, and the New Territories are in turn connected to mainland China across the Sham Chun River (Shenzhen River). In total, Hong Kong has 236 islands in the South China Sea, of which Lantau is the largest. Hong Kong Island itself is the second largest and also the most populated. Ap Lei Chau is the most densely populated island in the world.

The name "Hong Kong", literally meaning "fragrant harbour", is derived from the area around present-day Aberdeen and Wong Chuk Hang on Hong Kong Island, where fragrant trees were once abundant and widely exported. The body of water between Hong Kong Island and Kowloon Peninsula is Victoria Harbour, one of the deepest natural maritime ports in the world. The landscape of Hong Kong is fairly hilly to mountainous with steep slopes. The highest point in the territory is Tai Mo Shan, at a height of 958 metres (3,142 ft). Lowlands exist in the northwestern part of the New Territories.

Subtropical climate with distinct season. Typhoon season is May to November. When a typhoon is approaching, warnings are broadcast on TV and radio, and signals indicate the storm's distance from Hong Kong. If a typhoon comes near (Signal 8), business and shops close down and flights may be cancelled. There is a separate warning for heavy rains.