Tuen Mun, also known as Castle Peak, is an area located in the west of the New Territories in Hong Kong. It is situated near the mouth of the Tuen Mun River and Castle Peak Bay. As of 2025, the region serves as a modern residential hub with a population of approximately 540,000 people.
The area has a long history as one of the earliest settlements in Hong Kong, with origins dating back to the Neolithic period. In more recent history, it was notably home to many Tanka fishermen who gathered at Castle Peak Bay.