Halong Bay Geography Values

Situated in the northeast region of Vietnam, Ha Long Bay is a part of the Gulf of Bac Bo, and comprises Ha Long City, the township of Cam Pha and part of the island district of Van Don. To the southwest it is bordered by Cat Ba Island, the mainland coast extends 120 km. Ha Long Bay stretches between the 106º58 and 107º22 eastern meridians and the 20º45 and 20º50 northern parallels.


Ha Long Bay covers a total area of 1,553 sq. km, including 1,969 islands of various sizes, 989 of which have been given names. There are two kinds of islands,limestone and schist, which are concentrated in two main zones: the southeast (belonging to Bai Tu Long Bay), and the southwest (belonging to Ha Long Bay). The average geological age of the islands is between 250 and 280 million years old.

The densely concentrated zone of stone islands, grottoes and caves, world famous for its spectacular scenery, forms the central zone of Ha Long Bay, o­ne of UNESCO’s World Heritage Sites. This protected area covers 434 sq. km, comprises 775 islands and forms a triangle with the Dau Go Island (Driftwood Island) to the west, the Ba Ham Lake (Three Shelter Lake) to the south, and the Cong Tay Island to the east. The regions immediately surrounding the area were classified as a national site by the Ministry of Culture and Information in 1962.


Ha Long Bay is located in both a tropical and a temperate zone. There are four distinct seasons evident in each year. The annual average temperature is 22,8ºC, the average temperature in summer is 26,4ºC, and the hottest temperature is 35,7ºC. The average annual rainfall is 2,005.4 mm. The period from May to October receives the more significant rainfall and winter lasts from 4 to 5 months. Between the two main seasons are a shorter spring and autumn. The period from August to October is typhoon season.


The great national poet, Nguyen Trai, has called Ha Long Bay: “a wonder of the earth erected towards the high sky.” It is also a place closely linked to Vietnam’s history with such famous geographical names as: Van Don (site of an ancient commercial port); Poem Mountain (with engravings of many poems by emperors and other famous people of the past); and Bach Dang River (the location of three fierce naval battles fought against foreign aggressors).

This is not all:  Ha Long has been proven by scientists to be o­ne of the first locations of human existence in the area, with such archaeological sites as Dong Mang, Xich Tho, Soi Nhụ and Thoi Gieng. It is also a region of highly concentrated biological diversity with many varied ecosystems including salt water-flooded forests, coral reefs and tropical forests, and featuring thousands of diverse species of animal and plant life.

While exploring the bay, it’s hard not to feel lost in some legendary world of stone islands. There is an island resembling a man standing and looking towards the mainland. Dragon Island looks like a dragon hovering above the turquoise water. Yet another island, La Vong, resembles an old man fishing, and was named after a famous Chinese mandarin who abandoned his position to become a fisherman. There are also the islands of the Sail, the Trong Mai Islet  (Cock and Hen Islet), which look like a pair of chickens lovingly playing with each other above the sea; and the Dinh Huong Islet (Incense Burner Islet), all of which bear astonishing resemblance to their namesakes. The forms of the islands change constantly, depending o­n the light and the angles of view.

At the core of Ha Long Bay are wonderful caves and grottoes such as: Thien Cung Grotto (Heavenly Residence Grotto), Dau Go Grotto (Driftwood Grotto), Sung Sot Grotto (Surprise Grotto) and Tam Cung Grotto (Three Palaces Grotto).

Because of its unique value, at the 18th Session of UNESCO’s Council of World Heritage held in Thailand in 1994, Hạ Long Bay was officially placed o­n the list of World Natural Heritage Sites. In 2000, UNESCO recognized Ha Long Bay as a World Heritage Site for the second time,  for its geographical and geomorphologic values.