The three regions
It is conventional to divide Vietnam into three distinct regions, corresponding to the divisions adopted by the French and the Vietnamese vision of their own country: the north or Bac-bô (Tonkin), the center or Trung-bô (Annam) and the south or Nam-bô (Cochinchina). Nevertheless, from a geographical point of view, these three regions do not present a coherent picture of the country's diversity.
The reliefs
Vietnam is essentially a country of hills, mountains and high plateaus. There are three main mountainous zones in Vietnam: the northwestern zone, on the right bank of the Red River; the north/northeastern zone, on the left bank of the Red River; and the Truong Son range, which separates Vietnam from Laos and part of Cambodia.
The north-west zone. With mountain ranges of varying heights and plateaus running parallel to each other in a north-west-south-east direction, the area to the north-west of the Red River valley is the most rugged. The Hoang Liên Son range, the eastern extension of the Himalayan complex, is jagged with steep, almost vertical peaks that are the highest in the country. In Lao Cai province, to the south-west of the high-altitude resort of Sapa, Fan Si Pan, the highest peak in Indochina, rises to 3,147.3m. Its rugged beauty has unfortunately been disfigured by the construction of a cable car.
The north/northeast zone. North of the Red River valley, in Ha Giang province, several mountain ranges have peaks rising above 2,000 m (Tây Côn Linh, 2,431 m; Kiêu Liêu Ti, 2,402 m). The Chay River massif and the Dong Van karst plateau (between 1,400 and 1,600 m altitude), rich in spectacular scenery and populated by ethnic minorities, are particularly recommended destinations for hiking enthusiasts. Further east, up to the coast of Quang Ninh province, a region of low mountains (the majority no higher than 1,000 m) and hills ("moyenne région"). A multitude of valleys lead to China. Since ancient times, the region has always been the scene of major traffic flows, the crossing point for invasions, migrations and trade.
The Truong Son Cordillera. Formerly known as the "Annamite Cordillera", it is often referred to as the "backbone" of the country. The term "cordillera" is simplistic, however, since it generically encompasses a succession of ranges and plateaus that do not all belong to the same geological unit. The Truong Son Cordillera stretches 1,200 km from north to south, from Thanh Hoa province to Lâm Dông province. It separates Vietnam from Laos. Several passes allow passage between the two countries. In Quang Binh province, north-west of Dông Hoi, the Mu Gia pass (418 m) was the starting point of the famous Hô Chi Minh trail.
South of the Hai Van Pass (or "Cloud Pass", north of the city of Da Nang), in the provinces of Kontum, Gia Lai, Dak Lak, Dak Nông and Lâm Dông, is a massif with a different geological history, characterized by high plateaus once covered by forest and savannah, the cradle of the indigenous peoples. Thanks to the richness of its red basalt soils, this area of high plateau (in Vietnamese, Tây Nguyên) is now specialized in large-scale agricultural production: coffee, tea, pepper, cashew nuts, rubber..
Karst relief. Karst formations are a distinctive feature of the Vietnamese landscape. The spectacular maritime landscape of Halong Bay, made up of hundreds of limestone islands and islets jagged by wind, sea spray and the passage of centuries, eroded by the obstinacy of sea currents and storms, and hollowed out by labyrinthine caves, is inscribed on UNESCO's World Heritage List. Karst was originally a local term for the limestone plateaus of the north-western Balkans. By extension, it has come to apply to any limestone region with related characteristics. Several factors combine to explain the genesis and evolution of karsts, including tectonic movements, the nature of the rock, vegetation and climate. In Vietnam, karst massifs are concentrated mainly in the north, as an extension of the world's largest karst region, that of south-eastern China. The coastal zone, with Halong Bay and Cat Ba Island, is well known, but other sites are also remarkable, including the aforementioned Dong Van plateau in the far north of the country; the Cao Bang massif in the northeast, where you can visit the Ban Giôc waterfalls; and the "terrestrial Halong Bay" in Ninh Binh province, south of Hanoi. Last but not least, the Phong Nha-Ke Bang National Park in central Vietnam (Quang Binh province), also on UNESCO's World Heritage List, is home to an extraordinary underground network, including the Son Doong cave, the largest in the world.
These natural wonders have been the setting for blockbuster films such as Indochine (by Régis Wargnier, 1992), shot in Halong Bay and Ninh Binh province, and more recently, Kong: Skull Island (J. Vogt-Roberts, 2017), shot in Halong Bay, Ninh Binh province and Phong Nha-Ke Bang National Park. In addition to their scenic interest, the karst massifs are also ideal for sporting activities, including rock climbing, especially on Cat Ba Island.
The rivers
Between the mountains and the sea, two deltaic plains - the Red River delta to the north, the Mekong delta to the south - are linked by a narrow coastal strip. The plains occupy just one-fifth of the total surface area, but are home to four-fifths of the population. Life on the deltaic plains depends largely on flooding. During the high-water season, rivers carry 80% of their total annual flow, compared with 20% during low-water periods. River banks are submerged, sometimes up to +6 or +12 m (+12.3 m in Hanoi in 1945, while some of the city's streets are only +4 m high), and their course is changeable and uncertain over part of their length. Water plays an essential role in the Vietnamese imagination. For the delta farmer, taming the land means first and foremost mastering the water. In reference to this osmosis, to speak of their "country", the Vietnamese use the term dât-nuoc, which translates as land-water.
The Red River delta. To the north, the Red River delta(BacBô, in Vietnamese), an ancient gulf filled by the alluvial deposits of the Thai Binh river(sông), but above all by the Red River. The 1,200 km-long Red River rises in the highlands of China's Yunnan province. It is at Lao Cai (1,180 km from the sea and 800 m above sea level) that the Red River enters Vietnam. Up to Yên Bai, the valley remains straight and deep. The river swells downstream from its tributaries, the Rivière Noire(sông Da) and the Rivière Claire (sông Lo), which also descend from southern China. It enters the delta near the town of Viêt Tri. It then meanders lazily towards its many mouths. During the high-water period (June to October), due to the dual action of snowmelt (upstream, in the Chinese part) and monsoon rains, the Red River's floods can be very high, occurring in rapid, irregular succession. This has always necessitated the construction of a system of dykes, which over thousands of years have shaped the delta's landscape. In 1108, under the Ly dynasty, annals record the first large-scale construction of dykes, but the Red River is thought to have been dammed as early as 43 CE. The Red River delta was the earliest concentration point of the Viêt, mentioned as early as the 3rd century BC, and the center of a civilization based on irrigated rice cultivation and on cultural practices and customs closely linked to water, which are still deeply imprinted on today's villages.
From the Red River delta to the Mekong delta, a string of small coastal plains stretches out, which, south of the Ngang pass (Hoanh Son gateway, known as the "Annam gateway", between the provinces of Ha Tinh and Quang Binh), are divided by the foothills of the Truong Son mountain range, which juts out to the coast.
The Mekong delta. The Mekong delta(Nam Bô, in Vietnamese) is also an ancient marine gulf filled in by the alluvial work of a hydrographic network comprising the Dông Nai river and the Mekong river. The Mekong, the longest and most powerful river on the Indochinese peninsula, rises in the highlands of Tibet (in China's Qinghai province) at an altitude of 5,000 m, flows through China's Yunnan province, where it is known as the Lancang Jiang ("turbulent river"), through Burma, Laos, Thailand and Cambodia, completing a journey of some 4,500 km south of Vietnam. At Phnom Penh (Cambodia), the Mekong splits into two main branches that continue into Vietnam, where they are called Tiên Giang and Hâu Giang. These two branches continue to branch out until they flow into the sea through nine estuaries (several of which are now silted up), a configuration that explains the Vietnamese name "River of the Nine Dragons"(sông Cuu Long). The Mekong plain, unlike that of the Red River, does not require the construction of dykes, as the annual flood rises slowly from June until reaching its peak in October. Farmers can therefore adapt the pace of their work. The Mekong Delta is criss-crossed by a dense network of canals and arroyos(rach), which criss-cross the region and are used to transport people and goods. The alternating tides of the estuaries play a fundamental role in the movement of boats and irrigation works. Thanks to the fertile silt deposited by flooding, the Mekong Delta is nicknamed the country's "rice granary", supplying half of the country's rice production and over 90% of Vietnam's rice exports. It also provides 70% of the country's fruit production. The Mekong is sometimes referred to as a "fish highway", but in the delta, fishing, while still an important sector, is competing with other activities, such as irrigation, drinking water supply and industrial uses. The importance of the Mekong Delta underlines the seriousness of the threats it faces today. The delta is one of the regions of the world most threatened by global warming and rising sea levels. Sea levels have risen by 20 cm over the last fifty years. Extreme and unpredictable climatic events follow one another, with prolonged droughts and devastating floods. During increasingly frequent periods of drought, the lack of water prevents adequate irrigation of arable land and reduces fishing resources. Low water levels also contribute to increased salinity due to seawater upwelling in the river. Seawater can penetrate up to 60 km inland, jeopardizing tens or even hundreds of thousands of hectares of production in Vietnam's "rice granary". In addition, the pumping of sand to satisfy the demand for concrete fuelled by the growth of cities in Southeast Asia is leading to erosion of riverbanks and subsidence of soil. Above all, the proliferation of upstream dams, particularly in China, is having harmful effects. The releases disrupt the river's flow, diminish fish stocks and retain most of the alluvium needed to fertilize the soil downstream. By the end of the century, thousands of square kilometers of the Mekong Delta could be submerged.
The coastline
Vietnam's coastline stretches over 3,000 km and offers a wide variety of landscapes. To the north lies the prestigious Halong Bay. Heading south, from Thanh Hoa to Binh Dinh provinces, cliffs are linked by magnificent beaches. In Phu Yên province, Cape Dai Lanh (Cape Diên or Cape Varella), the foothills of the Truong Son mountain range, is renowned for its beauty and for being the first to be touched by the rays of dawn. South of Quy Nhon, as far as Ninh Thuân province, a rugged, winding landscape is interspersed with wide bays. The most famous is Cam Ranh (Khanh Hoa province), south of Nha Trang, one of the most beautiful in the world. Beyond Cape Dinh (or Cape Padaran), in Ninh Thuân province, and as far as Vung Tau, the coastline is flat, bordered by dunes.
From the Gulf of Bac Bô (or Gulf of Tonkin) in the north to the Gulf of Thailand in the south, Vietnam has more than 3,000 offshore islands and archipelagos. Among those accessible and open to tourism, from north to south, are Cat Ba Island (the largest island in Halong Bay), Ly Son Island (Quang Ngai province), the Cu Lao Cham archipelago (Quang Nam province), the Côn Dao archipelago (or Poulo Condor, in Ba Ria - Vung Tau province), Phu Quôc Island (Kiên Giang province, in the Gulf of Thailand)..
In the open sea, there are the coral archipelagos of Hoang Sa (or Paracels; Vietnam's sovereignty there is now being violated by China) and Truong Sa (Spratleys). Vietnam's maritime domain is three times larger than its land territory. The South China Sea (Biên Dông [East Sea] in Vietnamese) is a semi-enclosed sea that communicates to the north with the Pacific Ocean, and to the southwest, via the Strait of Malacca, with the Indian Ocean. These busy waters - through which a third of the world's maritime traffic passes - are also rich in fish and hydrocarbons. This poorly demarcated maritime space is the subject of territorial disputes between riparian states, but tensions are now aggravated by China's increasingly aggressive policies to impose its sovereignty. Its maritime openness therefore gives Vietnam an important place in world geopolitics, particularly in an international context marked by the maritimization of issues and the shift of the strategic center of gravity towards the Pacific Ocean.
