Natural, geological, cultural and historical and biological significance

Natural beauty

Speaking of Ha Long, one must above all talk of the beauty of its water and sky. In a relatively small area of 1,553 sq. km, there are 1,969 islands rising from the sea.
Seen from above, Ha Long Bay resembles a light blue handkerchief dotted with emerald gems; sometimes clustered together, sometimes isolated. The clever artistic hand of creation has made thousands of stone islands simulating familiar personages or animals. Like the constellations of the night sky, it's possible to find a familiar form in every island of Ha Long Bay: one brings to mind a pair of chickens bobbing on the spacious water(Trong Mai island); another is like a giant tortoise with half-closed and sleepy eyes (Tortoise Islet); another is like an old monk joining his hands in prayer to Buddha with his face overlooking the sea (Monk Islet); yet another is like a giant incense-burner standing in the middle of the sea which used to pray heaven and earth (Incense burner islet). It is a safe bet that many other islands bearing familiar forms remain undiscovered in the mysterious bay.
The sea of Ha Long is deep blue water throughout all four seasons. In spring, sailing amidst the waves, the stone islands look to be bobbing on the water. As summer approaches and the sun is rising on the far horizon, they appear to awake in unison and rise from the blue depths. The whole bay is bright red, and then turns to blue as the crests of the waves run together towards the shore. Orchids and fig trees, growing from fissures in the stone, bloom with snowy flowers.
As a boat makes its way through this forest of islands by ways of meandering channels, sometimes stone seems to be spread in front of you; forming a wall heeding further progress. Once nearer, the wall appears to crack open as if letting your boat pass. The scenery disappears behind you as yet another panorama opens to your view. The winding route seems to be endless, but the beauty of Ha Long Bay does not consist only in the forms of its mountains, islands and the colour of its waters, but also in its infinitely rich system of grottoes and caves; concentrated mostly in the middle of the UNESCO-protected area. Heavenly Palace Grotto bears a modern and refined trait, while Driftwood Grotto is ample and grandiose and Surprise Grotto appears deeply secretive. There are many beautiful examples, closely linked with legends and popular tales, such as: Virgin and Male Grotto and the Fairy Grotto Lake. Each is a grandiose and refined natural architectural creation.
At sunset, when the mountains' shadows stretch out long across the bay, the water turns grey-blue, before suddenly transforming to a crimson red as the last of the sun's rays reach the far away islands. For one short instant, the whole scene mingles into one colour, and then all light is extinguished. After the moon climbs into the sky, the sea seems to be coated with silver, with the lights of Hạ Long City reflected on the surface of the water. It seemed that every islands, caves and beaches in Hạ Long closely linked with the legend and popular tale of love, of the heroic song for safeguarding country... Visiting Ha Long Bay is a good chance to witness the romantic and attractive love story, which happenedonly in the legend.
The 18th meeting of the Committee of the World Heritages of UNESCO which was held in Thailand on December 17th, 1994 officially recognized Ha Long Bay as a Natural Heritage of worldwide importance.

Geological significance

The most remarkable geological events in the history of the Bay in the last 1,000 years include the advance of the sea, the raising of the bay area and the strong erosion that has formed coral and pure blue and heavily salted water. This process of erosion by seawater has deeply engraved the stone, contributing to its fantastic beauty. Present-day Ha Long Bay is the result of this long process of geological evolution that has been influenced by so many factors. Some of the most remarkable are: the formation of the limestone layer of more than 1,000 m in thickness during the Carboniferous and Permian periods (240 to 340 million years ago); and the development of the Ha Long depression during the Neogene period (10 to 26 million years ago). The erosion process forming the limestone plain was most active in the Quaternary Pleistocene epoch (11,000 to 2 million years ago). It is because of all these factors that tourists now visiting Ha Long Bay are not only treated to one of the true wonders of the world, but also to a precious geological museum that has been naturally preserved in the open air for the last 300 million years.
At the beginning of the Cambrian era (500 to 570 million years ago), the area, which is now Ha Long Bay, was basically mainland, submitted to a process of rain erosion. At the end of the period, it was flooded, commencing the existence of Ha Long Bay. During the Odovic and Silurian periods (400 to 500 million years ago), the area of north-east Vietnam was basically a deep sea, submitted to the constant activity of tectonic plates. At the end of the Silurian period, it underwent a phase of inverse-motion that created mountains deep under the water. From the end of this period and throughout the whole Devonian period (340 to 420 million years ago), the area was subject to powerful forces of erosion from the hot and dry climate. At this point, Ha Long was part of a wide mainland that comprised most of today's East Sea and Chinese continental shelf. Due to tectonic activity, the Ha Long area and the entire north-east region were raised from the depths at the end of the Devonian period. In the later Carboniferous and Permian periods (240 to 340 million years ago), a shallow and warm sea reformed, which existed for approximately 100 million years. It created two kinds of limestone: the Cat Ba layer of the early Carboniferous period (450 m thick); and the Quang Hanh layer of the middle Carboniferous and the early Permian period (750 m thick). These two layers constitute the majority of the islands of the Bay.
Passing into the early periods of the Contemporary era (67 million years ago), Ha Long Bay existed in the environment of a high mountainous mainland due to the influence of strong mountain-forming phases. The middle of the Paleocene period saw these motions remain continuous and stable, while strong processes of erosion began, and after millions of years, a form of semi-highland topography took shape. The continuation of this erosion has progressively cut the highlands into blocks with altitudes similar to today's mountains.

Into to the Quaternary era, the process of erosion began dissolving the limestone-rich region of Ha Long. The islands of today's Ha Long Bay are basically remnants of these mountains flooded during the early Holocene period. Rainwater flowed into crevices in the limestone that had formed from tectonic activity. This steady erosion constantly widened the cracks, eventually creating today's formations. The middle and late Pleistocene epoch (11,000 to 70,000 years ago) marks the period when the famous caves and grottoes of the area formed.
The Holocene period (from 7,000 to 11,000 years ago) is notable for the advance of the sea. This movement reached its peak 4,000 to 7,000 years ago and forming today's Ha Long Bay. After that, 3,000 to 4,000 years ago, with the sea in a steady process of recession, Ha Long culture began to develop. At the beginning of the late Holocene epoch, the level of the water once again increased, forming a marshy floor of canals and streams, and creating the water marks that can be seen on the stone cliffs of today.

Cultural and historical value

The beauty of Ha Long Bay is made up by its mountains, water, clouds, caves and grottoes. Many, however, do not realise that Ha Long was also the cradle of an ancient people who helped create the present Ha Long culture.
At the end of 1937, a Swedish-national archaeologist named Anderson, together with two French archaeologist sisters named Conani, journeyed for months through the sea of Ha Long. They climbed mountains, visited caves and explored the coastline, finding many stone artefacts: axes, grinding tables, sewing needles and jewellery. They called the culture that formed these remnants "Ngoc Vung". In the months and years that followed, Vietnamese archaeologists continued their research and made many excavations that resulted in the discovery of more archaeological sites, such as Dong Mang, Xich Tho and Soi Nhu. Through an area of some hundreds of square kilometres, they discovered many stone artefacts and pieces of broken designed pottery.
Throughout its development, Ha Long has had a particularly important position; being situated on the communication routes between China, Japan and Thailand. Gradually, it became the centre of cultural and commercial exchanges between these countries and ancient Vietnam. The book "Comprehensive History of Dai Viet" reads: "In the second month of the spring of the year of Ky Ty, the 10th year under the reign of Ly Anh Tong King (1149), the commercial port of Van Don was established." In the long period overlapping the Ly, Tran and Le dynasties, Van Don was a hosting venue of busy commercial and cultural exchanges between Vietnam and its South-East Asian neighbors. A remaining vestige of the ancient commercial port is Cai Lang Wharf (Quan Lan). Van Don is also a site that witnessed glorious feats of war against the invasion of the Yuan-Mongols aggressors. It was here that the enemy, General Truong Ho, had an entire fleet of food supply boats set ablaze by Tran Khanh Du. This contributed greatly to the victory of Bach Dang.
Closely linked to this animated commercial centre were many religious architectural constructions; built to meet the requirements of both traders and the population that practiced Catholicism and Buddhism.
At Soi Nhu, researchers found three fossilised human skeletons. In particular, in the central zone of the present UNESCO World Heritage Site area, there have been recent discoveries of fascinating archaeological finds Me Cung, Thien Long and Tien Ong grottoes. The quantity of ancient shellfish in the Melina Spring, indicated by the 1.5 m-thick heaps of shells, amounts to hundreds of cubic metres.
The archaeological sites of the Ha Long culture are distributed everywhere, but are mostly visible on the sandy beaches of the coastline, and in these caves and grottoes: Ngoc Vung, Tuan Chau, Xich Tho and Dong Mang. There are also sites far from the coast, such as Thoi Gieng and Tien Ong. Wherever the remnants of the first peoples of Ha Long are found, they seem to bear a common characteristic: similar materials, techniques, forms and designs. Scientists have called it the "Ha Long culture in the late period of the new Stone Age."
In Cai Lang Wharf, along to 200m-long coastline scientists had found broken pieces of pottery and china forming a 0.6 m-thick layer. Ages date from between the Ly and Tran dynasties. Here, there are also foundations of ancient houses once built along the wharf. Apart from here, many other ancient wharves have been found, such as: Cong Dong, Cong Yen, Ngoc Vung, Quan Lan and Cai Bau. They have featured similar artefacts.

On Cong Dong Island alone, four pagodas were built. Among them, the Lam Pagoda is one of the most ancient in the area. It was built under the Tran Dynasty with three gates, a shrine to Buddha, anterior cult room and house of ancestors. On the north-east side of the pagoda was a tower, the remnants of which indicate it was a large and solemn construction.

Biological significance

Ha Long Bay has a very complicated structure with its meandering coastline and many river mouths. Rich and diversified sources of food for many species of plants and animals are also found here. In particular, the bay, partitioned by thousands of large and small islands, creates areas of water with an average and stable sea level. Meanwhile, the climate in Ha Long Bay is also very stable, with an average temperature of between 19 and 25ºC, and an average heat radiation rate of 17 kcal/ sq. cm/ month. The average rainfall ranges from 2,000 to 2,200mm/ year.
These favourable conditions have seen the development of many varied ecosystems.
Scientific research findings reveal that Ha Long Bay features ecosystems of a tropical ocean region, such as: salt water-flooded forests, coral reefs and tropical rain forests.
In the sea surrounding Ha Long, coral grows in many places, but is densely concentrated on the eastern and southern sides, far from the mainland. According to research conducted by scientists from the Oceanographic Institute, Ha Long Bay is home to 163 species of coral, from 44 lines of descent and 12 families. Coral reefs are distributed everywhere, generally at a depth of 4 to 6m. The coverage rate of coral reef is 30% on average, but there are areas where it attains 70 to 80%, such as at Cong Do and Bo Hung. The coral forests of Ha Long Bay are a wonderful sight, with many extraordinary shapes and diversified colours. When the tide flows, the coral moves with the water, pumping as rhythmically as a heartbeat. At the same time, the reefs are residence to a great number of species: fish (107 varieties), water plants, algae and transitory animals and plants.
The salt water-flooded forests also offer especially interesting scenery along the coastline of Ha Long Bay. These forests are chiefly concentrated in the zones of Tuan Chau, Cua Luc and Ba Che. Many species of salt water-flooded plants, the most diversified collection in Northern Vietnam, are found here. Also living in these flooded forests are a great many species of animals: migrating birds (37 species), sea-bottom animals (81 species) and fish (90 species belonging to 55 families). In particular, bottom-feeders account for 61% of the total species in the whole tidal region, with many species being of great economic value: arcae, meretrixes and all kinds of crustaceans.
The tropical rain forest ecosystem also features a rich quantity of species: peg, Bassia and Teak trees. This is the habitat of various rare and precious creatures: deer, weasels, squirrels and in particular, white-tabby and red-haired monkeys.
At the same time, there is a system of small caves along the sea, which are the living and development places for many animals and plants: seaweed, water plants, algae, fish and shrimp. Deeper into the water, there are also many species of shrimp, fish (almost 1,000 species), abalone and other sea-specialities; harvested every year to the tune of several thousand tons.