Ha Long Bay
Ha Long Bay was first listed as a UNESCO World Heritage Site in 1994, in recognition of its outstanding, universal aesthetic value. In 2000 the World Heritage Committee additionally recognised Ha Long Bay for its outstanding geological and geomorphological value and its World Heritage Listing was updated.
In October 2011, World Monuments Fund included the bay on the 2012 World Monuments Watch, citing tourism pressures and associated development as threats to the site that must be addressed. The goal of Watch-listing is to promote strategies of responsible heritage-driven development for a sustainable future.
In 2012, New 7 Wonders Foundation officially named Ha Long Bay as one of New Seven Natural Wonders of the world.
Ha Long Bay is also a member of the Club of the Most Beautiful Bays of the World.
Ha Long Bay has an area of around 1,553 km2 (600 sq mi), including 1,960–2,000 islets, most of which are limestone. The core of the bay has an area of 334 km2 (129 sq mi) with a high density of 775 islets.The limestone in this bay has gone through 500 million years of formation in different conditions and environments. The evolution of the karst in this bay has taken 20 million years under the impact of the tropical wet climate. The geo-diversity of the environment in the area has created biodiversity, including a tropical evergreen biosystem, oceanic and sea shore biosystem. Ha Long Bay is home to 14 endemic floral species and 60 endemic faunal species.
Historical research surveys have shown the presence of prehistoric human beings in this area tens of thousands years ago. The successive ancient cultures are the Soi Nhu culture around 18,000–7000 BC, the Cai Beo culture 7000–5000 BC and the Ha Long culture 5,000–3,500 years ago. Ha Long Bay also marked important events in the history of Vietnam with many artifacts found in Bai Tho Mountain, Dau Go Cave, Bai Chay.
The climate of the bay is tropical, wet, sea islands, with two seasons: hot and moist summer, and dry and cold winter. The average temperature is from 15–25 °C (59–77 °F), and annual rainfall is between 2 and 2.2 metres (6.6 and 7.2 ft). Ha Long Bay has the typical diurnal tide system (tide amplitude ranges from 3.5–4 metres or 11–13 feet). The salinity is from 31 to 34.5MT in the dry season and lower in the rainy season.
Three main types of caves
The first group of caves is old phreatic caves which include Sung Sot, Tam Cung, Lau Dai, Thien Cung, Dau Go, Hoang Long, Thien Long. Nowadays, these caves lie at various high levels. Sung Sot cave is on Bo Hon island. From its truncated entrance chambers on a ledge high on the cliff, a passage of more that 10m high and wide descends to the south. Tam Cung is a large phreatic fissure cave that developed in the bedding planes of the limestone dividing the fissure cave into three chambers. Lau Dai is a cave with a complex of passages extending over 300m opening on the south side of Con Ngua island. Thien Cung and Dau Go are remnants of the same old cave system. They both survive in the northern part of Dau Go island at between 20 and 50m above sea level. Thien Cung has one large chamber more that 100m long, blocked at its ends and almost subdivided into smaller chambers by massive wall of stalactites and stalagmites. Dau Go is a single large tunnel descending along a major set of fractures to a massive choke.
The second group of caves is the old karstic foot caves which include Trinh Lu, Bo Nau, Tien Ong and Trong caves. Foot caves are a ubiquitous feature of karst landscapes which have reached a stage of widespread lateral undercutting at base level. They may extend back into maze caves of stream caves draining from larger cave systems within the limestone. They are distinguished by the main elements of their passages being close to the horizontal and are commonly related to denuded or accumulated terraces at the old base levels. Trinh Nu, which is one of the larger foot caves in Ha Long Bay with its ceiling at about 12m above sea level and about 80m in length, was developed in multiple stages. Bo Nau, a horizontal cave containing old stalactite deposits, cuts across the 25o dip of the bedding plane.
The third group is the marine notch caves that are a special feature of the karst of Ha Long Bay. The dissolution process of sea water acting on the limestone and erosion by wave action crates notches at the base of the cliffs. In advantageous conditions, dissolution of the limestone allows the cliff notches to be steadily deepened and extended into caves. Many of these at sea level extend right though the limestone hills into drowned dolines which are now tidal lakes.
Weather In Halong Bay
Although you can travel to Halong Bay all year round, there are some better days to visit the Bay than the other. Normally, the best time to visit the Bay is from March to May and from October to December. However, the weather has now seen changes which make the parameter of what is called “the best time” no longer 100% accurate. That being said, any day can be a good day in Halong Bay.
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