Bach Long Vi island is located in the Gulf of Tonkin, about halfway between Hai Phong (Vietnam) and Hainan Island (China). The island is an offshore district of Haiphong City. Fishing comprises the majority of economic activity in the Gulf of Tonkin, and Bach Long Vi is a major nursery and harvesting area for fish eggs. More than 50 species of commercial fish are abundant in the area (ADB 1999).

In Vietnamese, "Bạch Long Vĩ" means "The Tail of the White Dragon". This name has its root from an ancient Vietnamese legend. According to the legend, when the Vietnamese were fighting Chinese invaders, the gods sent a family of dragons to help defend the land. This family of dragons began spitting out jewels and jade. These jewels turned into the islands and islets dotting the sea, linking together to form a great wall against the invaders. The people kept their land safe and formed what later became the country of Vietnam. After that, dragons were interested in peaceful sightseeing of the earth, and then decided to live here. The place where the mother dragon descended was named Hạ Long meaning "Descending Dragon", the place where the dragon's children attended upon their mother was called Bái Tử Long island (Bái: attend upon, Tử: children, Long: dragon), and the place where the dragon's children wriggled their tails violently was called Bạch Long Vỹ island (Bạch: white- color of the foam made when Dragon's children wriggled, Long: dragon, Vỹ: tail).Before the 20th century, the island used to be called "Vô Thủy" which means "no water" since there was no water source on the island.